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Did removing lead from petrol spark a decline in crime? (bbc.com)
213 points by austinz on April 20, 2014 | hide | past | favorite | 270 comments



I what some people here seemed to be missing, is this correlation isn't just lead was removed from the environment and 23 years later crime went down. It's that various areas has differing degrees of lead pollution and started reducing it at different times.

The places that reduced lead pollution first, saw the drop in crime first, the places that reduced it later saw the drop later. The eras that initially had high levels of lead had a larger drop in crime than areas that always had a low level.

And it's not just the USA either. The pattern holds pretty accurately for various nations around the world, like in Europe. Those who banned leaded fuel first, saw the drop in crime first, those who banned later, saw the drop later.

And these nations had massively differing crime policies. Some nations increased prison sentences to try and deter crime, and crime went down. Some nations put a huge effort into reforming criminals, and crime went down. And some nations cut prison sentence, and crime went down.


If the theory is true it could also account for the fact that violent crime is more abundant per capita in urban areas compared to rural areas since lead from gasoline will obviously be more abundant in cities with lots of cars per square mile compared to rural areas with very few cars.

Here's a link (2 minutes of googling..) showing the difference. http://www.victimsofcrime.org/library/crime-information-and-...


Yeah pretty sure that's because of other more obvious factors:

* Greater anonymity in cities * Higher population density * Juxtaposition of poverty and wealth


Are these factors so obvious?

As an example poverty is most prevalent in rural areas according to this study: https://www.google.dk/url?sa=t&rct=j&q=&esrc=s&source=web&cd...

Be careful of citing "obvious", it can be deceiving.

Note that I'm not arguing that lead in gasoline proves a definite link between crime in rural vs. urban areas, just noting that there is the same correlation as stated in the article. I merely thought it was interesting, and that it might be the same effect at work due to the dilution of lead in rural areas because there are fewer cars.


Juxtaposition of poverty and wealth, not poverty itself. In most American cities somebody from a poor neighborhood can walk a few blocks and mug a rich person at knifepoint, whereas in the average poor rural area, there aren't really any rich people around to rob.


That's true but the vast majority of urban crime is poor on poor and takes place in the neighborhood where the victim and perpetrator both live.


this is at best an anecdotal point, and seems more like something you just thought up. Is there any substance to this? Is crime in urban areas more prevalent because it is a shorter distance to walk for a potential mugger to get to a rich person he can mug?

This just doesn't seem very likely to me, but if you can back it up by numbers I'll gladly change my view.


> Is crime in urban areas more prevalent because it is a shorter distance to walk for a potential mugger to get to a rich person he can mug?

This is just a correlation, possibly meaningless, but an explanation for the decline in New York City crime over the last 30 years is that poor people can't afford to live there any more. It's just an opinion, true for most such views.

> ... but if you can back it up by numbers I'll gladly change my view.

Now that would be very difficult, even with the numbers. The number of poor people living in NYC is available, and the number of poor-on-rich crimes is available (both in sharp decline), but proving a connection between them is nigh impossible.


Why would that automatically lead to an increase in crime?

If you have wealthy areas, you have opportunities for less affluent people to get ahead through legitimate means. They have economic opportunities.

On the other hand an area that's entirely depressed is often infested with crime because there's no alternative to theft. The economic opportunities do not exist.


Higher population density seems obvious. Increasing density increases the opportunities for violence.

But, since violence is more often directed at people that are known, rather than strangers, I find the other two suspect.


You can be as sure as you like.

The fact remains that the concentration of lead in the living environment is the most strongly correlated measurable datum to crime rate than any other single factor.

If you compare factors directly relating to motives, methods, and opportunities (the crime triangle) in different cities, the correlations are still weaker than whether the population was exposed to lead pollution as children.

This is not the first article on this topic that has been published. None of them, as far as I am aware, have proven causation rather than correlation--probably because proving it would take 20+ years and be grossly unethical.

But nevertheless, it would be interesting to see what happens if one city decided to completely eradicate lead contamination from within its limits, and compare it against cities of similar character that chose not to do so over the next 30 years.


Not disagreeing outright, but there are studies[1] that link high-poverty areas with higher lead concentrations. There was also an interactive map, some time ago, that showed lead soil levels by zip code and they definitely seemed to match up with more problematic neighborhoods. Clearly, the factors you call out have an influence, but lead seems to be a part of that equation.

[1]: http://www.ncbi.nlm.nih.gov/pubmed/22752852

Edit: switched low with high.


(you mean high poverty areas correlated with lead concentration, right?)

My first guess would not be that lead causes poverty (is that what you are suggesting?), but that lead-producing activities (highways, factories, waste dumps) tend to be undesirable, and tend to be placed in poorer neighborhoods because poor people have less political power.


Yes, I do mean areas with high poverty areas or low income.

I am not really suggesting any particular cause of poverty, but lead-soil levels seem to have some negative effect. The more important suggestion is that its not just income disparity, anonymity and juxtaposition of poverty and wealth, if at all, that leads to higher crime rates in cities.

In fact, mixed-income neighborhoods have been linked to better social mobility, but that is getting off-topic.


I guess it's topical if it's about proper conclusions from statistics.

I think your conclusion, from correlation between lead concentration in soils to conclusiong "lead-soil levels seem to have some negative effect" -- is entirely unjustified.

The alternate hypothesis I mentioned seems as, or more, plasuble. That it's not lead-soil levels that are having any effect at all, but rather that lead-producing activities are socially undesirable, and end up in poor neighborhoods because poor people lack political power.

I suppose the scientific method would be to devise an experiment or investigation that would attempt to distinguish between these two hypothesis. Possibly people already have, and arguing about it in the academic literature now.

One danger of concluding causation from correlation in the 'big data' era is how easy it is to go hunting for correlations. If I test ketchup consumption against 1000 other variables, it may be fairly likely that I'll find a correlation against at least one of them. (If I flip a coin 10 times; and then do this experiment 1000 times, it's not unlikely that at least one of those 10-times iterations I'll get 10 ten heads). So maybe I find that ketchup consumption is very closely correlated with public transit availability, across cultures and times and governments. That doesn't really mean that ketchup causes public transit or vice versa, it just means that if you have enough data, you're going to find happenstance correlations.


It seems you are trying hard to find something in my statement with which to refute. I was merely pointing out that the GP's conclusions are probably incomplete, given the data we have on lead.

Most of my previous comments were quite non-committal. For instance, the phrase "lead-soil levels seem to have some negative effect" was cherry-picked for your analysis, and given much stronger meaning than intended. First, let's examine the word choice of "seem". It means "give the impression or sensation of being something or having a particular quality." This modifies the statement, to imply that the data "gives the impression" that there is "some negative effect". This is a much weaker statement than a hypothesis on the effect of lead-soil levels on poverty-stricken neighborhood. Perhaps, that statement would have been more clear if written as, "lead-soil levels seem to have an effect on crime". The implication from the sentence that follows is that the value of "some" is "crime".

It very well could be that lack of political power caused lead-producing activities to be concentrated in low-income neighborhoods. However, the issue at hand is not that lead-soil levels cause poverty; it's that lead-soil levels increase the incidence of crime. This point may not have been clear, as conceded above.

Indeed, correlation does not imply causation, but we know much about the health effects of lead [1] and its impact on decision making. We know that the correlation of crime rates with increasing and decreasing lead-levels, in a variety of situations, throughout many policies and governments, holds. We know both a pathway and have a strong correlation. Dismissing this as happenstance is unwise.

[1]: http://en.wikipedia.org/wiki/Lead#Health_effects


Those seem to absolutely be factors, perhaps the overwhelmingly influential ones, but the question is how influential is this leaded gas business. Where does it fit into the big picture?


All of those factors have increased in the past twenty years and yet crime continues to fall. Your explanatory paradigm needs reworking.


Yeah I'm pretty sure I'm gonna give more credence to scientific studies than Timmmmmm's opinion on what is obviouis.


This reminds me very much of the study that correlated legalized abortion with a decline in crime -- I believe it also showed it wasn't just a general global trend with legalized abortion and dropping crime, but that places that legalized abortion first saw crime drop first etc.

I think the conclusion is obvious: Removing lead from petrol lead to legalized abortion. Or was it vice versa?

But seriously, I think we need statistical analysis showing the correlation between legalized abortion and unleaded gasoline. Perhaps it would actually show that places that legalized abortion first actually WERE correlated with places that unleaded gasoline first.

It would be silly to assume causation there, even if the correlation were just as strong. Which would be a useful reminder about correlation and causation. Just because you have a correlation where causation is _plausible_ still doesn't mean causation.


It's always interesting when statistics correlate across multiple frames (time, location, etc.); however that still doesn't prove causality. I'm inclined to think that the causes behind an area being slow to remove leaded gasoline could also affect crime rates.


>I'm inclined to think that the causes behind an area being slow to remove leaded gasoline could also affect crime rates.

The statistics show a 20-year lag between the banning of leaded gasoline and reduction in crime rates. So even if "unwilling to ban leaded gas" and "high crime 20 years later" could be correlated, it seems less likely that the same things that cause "willing to ban leaded gas" are also the cause of "lower crime 20 years later".


That's not entirely true. One factor could be that less progressive urban areas are both less willing to remove lead from gasoline and less willing to fund community outreach programs. Community out reach programs may take years to gain traction and become effective. Banning gasoline is witnessed in a much shorter time frame. This would explain the lag between crime rate drops and banning of leaded gasoline.


Its interesting to model the biosphere hydraulically.

So lead from leaded gas drips into the barrel representing the local ecology, and the lead contaminant drips out of the biosphere at a rate that obviously must depend on local climate. Presumably lead contaminant flows into the oceans or gets buried in the ground at a rate dependent on local weather.

Yet the stats show a nearly perfect and consistent shift 20 years after the addition of lead to the environment stops. That's just biologically weird, like a part of brain development doesn't depend on local lead levels, but on the first derivative of lead levels or something.

It COULD make sense if lead only causes problems when inhaled. Not consumed in food, not drinking water, purely and exclusively inhaled. Even then, local dust storms and the like should totally mess with the supposed global 20 year effect latency.


Lead reacts with other elements! If it was as un-reactive as gold, it probably wouldn't be as toxic.

Just for starters, burning leaded gasoline can involve pure Lead, Lead(II) oxide, Lead(II) bromide, and Lead(II) chloride.

http://en.wikipedia.org/wiki/Tetraethyllead#Reactions


>It COULD make sense if lead only causes problems when inhaled

I think inhalation of engine exhaust is the main "delivery method" for lead pollution from leaded gasoline.


Perhaps another study should be done following individuals. It seems a decent attempt at disproving the hypothesis.

Take say 50 specific individuals ... actually look at where they lived each year of their lives, and estimate as accurately as possible their lead exposure. If they move cross country, "follow" them and estimate the change in lead exposure accordingly.

Once you have an assessment of the lifetime lead exposure of the 50 people, see if it predicts their levels of criminal behavior or aggression.


Crime is rare enough that you wouldn't get any sort of conclusive result from the variations in lead level among 50 people.

(Example: suppose 0.1% of people become murders in their lives, and lead is 100% responsible for every murder, and you had 2 groups of 50 people who had either tons of lead or no lead exposure at all; what will the result be? Likely, no murderers in your total group of 100 at all and certainly no difference between the two groups - despite extremely generous assumptions!)


I'm not sure that would work. The 20 odd year lag seems to be a generational gap, not a delay in concrete effects on any specific person.


What they might also be misssing -- and the article highlights this -- is that its not just a correlation analysis. There's also a fairly well-developed explanation for the causal mechanism that justifies the hypothesis -- lead has already been established to have significant effects on brain development and behavior (and been specifically linked problems in impulse control and executive functioning.)


Thank you for this really interesting comment.

I wonder if the lead could leave the body, and if the effects it had are somewhat reversed over time, for those that lived in environments with much traffic.

Do you have any idea about this?


If I remember correctly (haven't read this article), there's some sort of offset between decrease in lead and crime reduction, which seems to suggest that it is infants and young children who are affected, or lead actually affects the development of some areas of the brain (the offset was explained by the fact that infants and children don't usually commit crimes, but they do once they get slightly older).

So it is not lead itself, (or the presence of it in your organism) that makes you more likely to commit crimes, but having your brain development impaired by it while an infant that does.

I don't have time to search for the article, but it came up with the last discussion on this topic here.


My understanding is that lead poisoning during pregnancy and early childhood causes the brain to not develop normally, which is what likely leads to a propensity to criminal behavior. Removing lead from the body later in life would be unlikely to help, as the damage has already occurred.


Not to mention the fact that it makes a lot of sense. Statistics is not the only evidence supporting this theory.


Statistics is the means of testing whether or not something is evidence.

I understand what you meant, it's an intuitive conclusion, one that doesn't seem like magic. But, something making sense usually does not correlate with or serve as evidence of it being true.


something making sense usually does not correlate with or serve as evidence of it being true.

It's true that statistics is required to be sure if something is true, but it's a priori far more likely that a rise in violent crime is caused by a substance known to damage people's brains than by, say, the gravitational influence of Pluto. And we rightly demand careful confirmation when someone finds a particle traveling at a velocity greater than c than when it is found to be traveling at a velocity less than c.

EDIT: And more to the point, I hope you don't find the hypothesis that violence in the 70s caused leaded gasoline in the 50s as that leaded gasoline in the 50s caused violence in the 70s, and that you would agree that one of those two hypothesis needs more evidence before we accept it. Granted, it could easily be some more complicated net of causality, but just between those two.


I didn't wish to bring in Bayesian approaches here so as to keep it simple. You are correct in your assertion about likeliness given a priori intuition, and I agree with the linking.

But, there is a stark contrast between leveraging prior information to strengthen your estimates and stating that prior information serves as evidence or correlates with outcomes, which was my original assertion.

Either way, I'm a big fan of leveraging common sense (viz Bayesian approaches) so I can't disagree.


If prior information didn't correlate with outcomes then it would provide no value and shouldn't be used.


If you take a bayesian approach it affects your prior.


The answer to any headline question is supposed to be 'No!'

Thank you.


Aren't the politics required to enforce lead reduction the same that would tackle crime, though? I don't think there are many enviromentally-friendly corrupt parties.


The crime reduction reliably occurs 20 (23, from the graph?) years after the lead reduction; there's no response in the crime rate until the less-lead-exposed babies have become adults.

The politicians who tackled crime (or didn't, or did whatever) 20 years ago haven't been in power most of the time since then, generally.

I've read about this theory before; it's impressive and (to me, at least) pretty persuasive.


To paraphrase a comment I made further up, banning lead in gasoline is a binary initiative that doesn't take a long time to initiate. Cracking down on crime is a longer process.


You wouldn't think there were many corrupt religious parties either, but politics doesn't always work that way.


Huhwhat? What's corruption got to do with it?


Mildly off topic but Bill Bryson is interesting on how we ended up getting lead in petrol in the first place http://enconv.org/docs/index-26824.html?page=11

Except: "So in 1923 three of America’s largest corporations, General Motors, Du Pont, and Standard Oil of New Jersey, formed a joint enterprise called the Ethyl Gasoline Corporation (later shortened to simply Ethyl Corporation) with a view to making as much tetraethyl lead as the world was willing to buy, and that proved to be a very great deal. They called their additive “ethyl” because it sounded friendlier and less toxic than “lead” and introduced it for public consumption (in more ways than most people realized) on February 1, 1923.

Almost at once production workers began to exhibit the staggered gait and confused faculties that mark the recently poisoned. Also almost at once, the Ethyl Corporation embarked on a policy of calm but unyielding denial that would serve it well for decades. As Sharon Bertsch McGrayne notes in her absorbing history of industrial chemistry, Prometheans in the Lab , when employees at one plant developed irreversible delusions, a spokesman blandly informed reporters: “These men probably went insane because they worked too hard.” Altogether at least fifteen workers died in the early days of production of leaded gasoline, and untold numbers of others became ill, often violently so; the exact numbers are unknown because the company nearly always managed to hush up news of embarrassing leakages, spills, and poisonings. At times, however, suppressing the news became impossible, most notably in 1924 when in a matter of days five production workers died and thirty-five more were turned into permanent staggering wrecks at a single ill-ventilated facility. ..."


Midgley is perhaps among the most damaging engineers the world has known: he is responsible for both tetraethyl lead additives to gasoline (the subject of this article) and chloroflorcarbons, responsible for damaging the Earth's ozone layer:

http://en.wikipedia.org/wiki/Thomas_Midgley,_Jr.

This story is also a very strong argument toward both regulation of markets due to externalities (lead in gasoline and paint were defended vigorously by their respective industries for decades), and of the argument that there are some products and services which, despite being profitable to those dealing in them directly, impose a net negative cost to society as a whole.

Such activities are often difficult to recognize strictly because of the nature of externalities: they're diffuse, affecting many individuals, often incrementally in a small way, often indirectly and, in the case of environmental lead, with impacts lagging cause by decades.

This is also a very powerful case of negative impacts accruing largely due to socioeconomic circumstances not ascribable to the conscious and voluntary decisions of those directly affected: neither the infants and children exposed to lead, nor the victims of the criminal acts they transacted on a probabilistically greater scale, had entered into any sort of voluntary or legally recognized agreement with the manufacturers of leaded gas and paint. Punches a bit of a hole in that whole libertarian argument which promptly ... sinks like a lead balloon.


This has come up before with the Mother Jones article http://www.motherjones.com/environment/2013/01/lead-crime-li... This article is better in my opinion. Good discussion on HN then too. https://news.ycombinator.com/item?id=5006368


For those searching for a TL;DR of the article, here is a much shorter blog post by the same author talking about the different kinds of evidence supporting the thesis:

http://www.motherjones.com/kevin-drum/2013/01/lead-and-crime...

One quote:

> There are now multiple rigorous studies using different methodologies that demonstrate this correlation at the city level, the state level, the national level, and in different countries at different times.


Lead paint really can't be mentioned without bringing up the name, work, and abuse heaped upon Herbert Needleman who drew many of the associations between the use of lead in paint and brain damage to children, especially inner-city and underprivileged youth:

http://www.washingtonian.com/articles/health/why-is-lead-sti...

For his efforts, Needleman endured years of attacks denigrating the quality of his research and his integrity as a scientist. In 1982 the industry-funded International Lead Zinc Research Organization (ILZRO) went to the Environmental Protection Agency to accuse Needleman of scientific misconduct. The EPA convened a committee of experts, which concluded that Needleman’s study had not proved a connection between lead exposure and a child’s mental development. Needleman countered that the committee report contained serious mistakes. The EPA agreed, reversed the committee’s findings, and lauded Needleman’s “pioneering study,” saying it confirmed a “significant association” between lead exposure and childhood intelligence.

The ILZRO hired the public-relations firm Hill & Knowlton to publicize the original committee’s criticisms of Needleman.

Two scientists led the next attack on Needleman. One was Sandra Scarr, a developmental psychologist at the University of Virginia who had been a member of the EPA committee that disputed Needleman’s study. The second was Claire Ernhart, a developmental psychologist at Case Western Reserve University in Cleveland, who called Needleman’s study “slipshod.” Beginning in 1983, Ernhart, who had conducted lead research, received about $50,000 a year from ILZRO for research support but denies being beholden to the lead industry or speaking on its behalf. Scarr claims not to have received money from ILZRO other than expert witness fees and likewise denied industry influence....

In all, the attacks on Needleman’s work and integrity and his defense against them dragged on for 15 years.

Intentional disinformation is a major theme of this (59 minute) lecture by Philip Mirowski, an economic historian (he focuses largely on global warming but the principles and rationale apply broadly to other cases of economically incentivized disinformation): http://www.youtube.com/watch?v=I7ewn29w-9I

Among other things, it references the work of Naomi Oreskes and Erik M. Conway, Merchants of doubt: how a handful of scientists obscured the truth on issues from tobacco smoke to global warming, and Robert N. Proctor's Golden Holocaust: Origins of the Cigarette Catastrophe and the Case for Abolition.

I discuss these at more length here:

http://www.reddit.com/r/deep_ecology/comments/1yum2c/life_an...


Thanks for the link to that lecture, it's rather amazing.


Sounds like the attacks of the global warming alarmists on people that question their theories.


Disputing flawed studies does sound like something that scientists who acknowledge human-caused global warming might engage in, yes. The same is true of, for example, vaccine-autism linking studies. This is in fact something that happens all the time in the scientific community. The better question is whether those scientists were getting paid large sums of money by industry in order to make those claims (hint: they aren't--in fact, the opposite is true, with virtually all global warming denialism organizations linkable to large private investments by the oil industry).


Care to tell me how many global warming denialists don't have ties, many strong, to the fossil fuel industry and/or conservative right-wing political causes?


Mother Jones....now there's a scientifically credible, impartial source.


It's been suggested that the removal of lead from fuels, paints, etc. may explain the fact that our IQs have risen since about the same time, and since leveled off somewhat.

http://en.wikipedia.org/wiki/Flynn_effect

Say what you will about environment, but the lead explanation seems to match historical data in all the ways we'd expect it to. Find something that lead does, and we find a trend showing its decline since we started eliminating lead.


I wonder how this interacts with IQ differences by ethnicity, given that historically some ethnic groups tended to live in inner cities where lead exposure would have been significantly greater.


This has been studied. Gains from the Flynn effect don't show a relationship to race effects in IQ.


Speaking of historical data: leaded plumbing is linked to the decline of the Roman Empire.


Are there reliable sources on that?

Also, using Lead Acetate[1] as an artificial sweetener probably didn't help matters.

[1] https://en.wikipedia.org/wiki/Lead%28II%29_acetate#Sweetener


Here's a good place to get started: http://penelope.uchicago.edu/~grout/encyclopaedia_romana/win...

although this argues that lead in plumbing was NOT a major source of poisoning.



[citation needed]


Reading the Wikipedia article seems to indicate that most of the rises in IQ due to the Flynn effect happened during the period when fuel lead levels were high.

Would they have risen faster without lead?


NPR just ran the story "Study: Half Of Jailed NYC Youths Have Brain Injury"

The study found nearly 50 percent of both boys and girls reported traumatic brain injuries that resulted in a loss of consciousness, amnesia or both. And they said 55 percent of those injuries were caused by assaults.

An estimated 60 percent of adult prisoners have a brain injury, according to a study of prisoners in South Carolina.

http://www.npr.org/templates/story/story.php?storyId=3045728...

The US justice system has become extreme in the pursuit of punishment vs treatment and rehabilitation.


That is vs 30-40% of the general population.

There's nothing unexpected here. Youths mostly go to jail for violence. The more fights you get into, the more likely you are to be injured. I'd imagine that there's a far larger percentage of number of jailed youths with knife scars than those in school. That doesn't mean knife scars cause people to end up in prison.


There's nothing unexpected here. Youths mostly go to jail for violence. The more fights you get into, the more likely you are to be injured. I'd imagine that there's a far larger percentage of number of jailed youths with knife scars than those in school. That doesn't mean knife scars cause people to end up in prison.

I'm no neurologist, but i suspect that a brain injury might change your personality more than a scar from a knife fight, possibly making you more likely to engage in criminal behaviour.


I see no reason why a head injury shouldn't equally change a personality to become less criminal. Head injuries have completely unpredictable effects. My core point is that prisons are full of violent people, and violent people punch and receive more punches, therefore are more likely to have brain injuries.


Sometimes head injuries do make you less likely to become a criminal. Very few people in comas and vegetative states commit crimes.


It's not really in pursuit of punishment either. It's in pursuit of putting taxpayer money into people's pockets.


There is plenty of money to be made in curing mental illnesses. A prison is a lot less profitable than a drug.


All other things being equal, maybe. But:

1) A prison is far more easily sold to the population that hospitalization or cures ("what, you mean we're paying for those criminals welfare?!").

2) Imprisonment is "business as usual" -- so less friction and investment needed to move things there (they already are like that).

3) Lots of prisons also exploit inmates' labor.

4) Prison keeps the annoying (to those people) black minorities at bay.


Drug development is extremely risky. A privately run prison is pretty much a government money spigot.


Presumably there is little overlap between individuals or organizations that can provide mental care and those that can provide prisons.


"Become"? When was it not?


Prisons were initially invented as correction facilities, rather than instruments of punishment. Before this, crime was mostly dealt with by physical punishment.


This is completely wrong. You might benefit from reading Foucault's Discipline and Punish.


Yup, Cosmos was on tonight, subject: lead. It's nice to see it got some brains fired-up.

PBS also had a great series the Poisoner's Handbook about different poisonous elements and the one about lead was more in-depth about leaded gasoline. Charles Norris was an amazing person! http://www.pbs.org/wgbh/americanexperience/features/introduc...


Sesame Street debuted in 1969.

Whenever I see stories like this, I wonder what sort of impact it has had.


Or to say the introduction of violent video games in the mid to late 90s and the rise in gun violence in schools in the last few years? Young children growing up with the increase exposure to violence could be related?


Or to say the introduction of violent video games in the mid to late 90s and the rise in gun violence in schools in the last few years?

Oh, you must mean this ( http://www.theesa.com/policy/scotus_chart.gif ) rise in violence.


I genuinely don't know whether violent video games implies more violent behaviour, but I am 100% sure that this chart doesn't prove or disprove anything.


You offered a suggestion that was based on a false premise. I posted a chart that shows that your premise was false -- nothing more, nothing less. You responded by pointing out that the chart doesn't "prove" anything. This is true. It can't prove causation, because there's no effect to observe in the first place. You might as well ask whether cell phone radiation is responsible for our present worldwide bubonic plague epidemic.

Your beef is with whoever told you that the world was becoming more dangerous, not those who post statistics that paint the opposite picture. Somebody lied to you. Find out why.


> You offered a suggestion that was based on a false premise.

I haven't, I am not taf2. I was just saying that this inverse correlation that you see may be due to other factors or may not even be statistically significant. We're missing a lot of data here (e.g. how does the juvenile crimes rate fluctuates prior to 1990).


The chart plots video game revenue and youngster violent crimes over time. If there is a correlation there, it is negative. It does disprove the theory of video game caused violence.


> If there is a correlation there, it is negative

Yes that's my main point: this plot does not prove the correlation.

If you look at a bigger picture e.g. (maybe here [1], altough it's not technically the same metric) there was a peak around 94. The peak and the relative low value before the peak cannot be explained by video games.

And that my second point: no one ever claimed that violence is only caused by video games. Clearly the blue curve is under the influence of (many) other factors, so it's very hard to determine whether there is a correlation without knowing these other factors.

But let me say it once again, it's a possibility that video games reduce violence. I am simply saying that if think this is the case because of this plot, you're probably biased.

[1] http://www.eji.org/files/juv%20murder%20rate%20drop_0.jpg


> Yes that's my main point: this plot does not prove the correlation.

I don't get your line of reasoning. Let's go through all the scientific method steps:

The hypothesis is: Videogames cause violent behaviour in youngsters.

The test for this hypothesis is: If videogames cause violent behaviour in youngsters, then we should find a positive correlation between the rise in popularity of videogames and youngster violence.

The hypothesis failed the test. The correlation either is not there, or it is there but is negative. We can conclude, from the fact that we did not find a positive correlation, that the hypothesis is false.


> We can conclude, from the fact that we did not find a positive correlation, that the hypothesis is false.

We could if it was a lab experiment where the only factor that varies would be the popularity of violent video games. But it's not.

It's entirely plausible the the increase of home entertainment has indeed reduced the rate of juvenile crimes. (kids don't stay in the street any more). Yet it doesn't say much about how violent games induce violent behaviours.


We can. If we didn't have to account for other factors, we wouldn't even require tools like correlation and linear regression. These are statistical tools needed to deal with signals affected by both error and multiple inputs. These characteristics do not prevent analysis, though care must be taken.

Your explanation is obviously possible, but it does not preclude my conclusion. If your explanation for the signal correlation is true, then video games account for comparatively little youngster aggression.

I am terribly sorry for the ad-hominem, but I think, at this moment, you need to brush up on statistics 101. The arguments used are typical of pre-statistical studies, and HN is really not the place to be taught fundamentals.


> I am terribly sorry for the ad-hominem,

That was a bit cheap but ok. Let me add more.

Here is the same data that I have reploted

http://imgur.com/fdtc0tH

This chart is less biased (y axis starts at 0) and the correlation is less obvious.

The correlation is actually -0.6557, which is significant but probably not as high as you would expect from the first chart. But ok the correlation between game software revenue and juvenile violence is probably here (we're talking about ~20 data points...). To go further and conclude anything about violent games, you would need at least the proportion of violent games among games, we don't have it here.

Here's the data that I've extracted from the pixel position. It's not 100% accurate, but it should be good enough.

    1990 412.999995
    1991 430.999995
    1992 448.999995
    1993 469.999995
    1994 495.49999995 
    1995 487.99999995 3.2		  
    1996 432.49999995 3.67407407407407
    1997 384.49999995 3.74179894179894
    1998 355.99999995 4.55449735449735
    1999 322.99999995 5.43492063492064
    2000 298.99999995 5.5026455026455 
    2001 291.49999995 5.90899470899471
    2002 276.49999995 6.92486772486772
    2003 285.49999995 7.06031746031746
    2004 270.49999995 7.33121693121693
    2005 279.49999995 6.92486772486772
    2006 297.49999995 7.26349206349206
    2007 286.99999995 9.43068783068783
    2008 288.49999995 11.6656084656085
    2009 261.49999995 16


Pac-Man was introduced in 1980. Many of the children who grew up with it have gone on to spend a lot of time eating pills in the dark while listening to electronic music. The link is clear.


I think you should give credit where it's due for that joke: http://en.wikipedia.org/wiki/Marcus_Brigstocke#Pac-Man_joke.


Huh, I had no idea it had any origin besides "some anonymous coward on the internet". Appreciate the link.


Okay, would you mind pointing out to me just when during this timeline you believe video games made a big impact...

http://en.wikipedia.org/wiki/List_of_school_shootings_in_the...


I've read about a couple of different explanations for changes in crime rates. I think freakanomics has discussed greater prevalence of abortions[1], and one thing I've heard in academic circles is that crime reporting has gotten better. You could actually make predictions with this article's question. There may have been areas where lead was used in petrol for longer than others, one could compare across regions and see if the time at which petrol was changed also adheres to drop in crime to see if there is still a correlation.

http://freakonomics.com/2005/05/15/abortion-and-crime-who-sh...


Levitt and Dubner wrote down a number of interesting theories about lots of things, but I think they overthought this one.

The crime rate rose and dropped pretty neatly along with the proportion of young men in society. The median age is much higher now than it was 30 years ago. Crime, especially violent crime, is a young man's game.

Perhaps they are right and roe vs wade was one of the factors in raising the median age, but it seems that people today want smaller families, and have more control over this than a generation ago. You can't assume that if a woman has an abortion, a miscarriage and two kids over her lifetime, she would have had four children if it hadn't been for the abortion and the miscarriage.


While I've been generally convined Freakonomics is to be considered suspect on this, the argument you present in the last paragraph doesn't counter it: the Freakonomics point was that absent abortion, people were forced into having children earlier when they were not ready to support them fiscally or emotively due to their situation, whereas with control of their fertility they can choose when they are best prepared and most desired them.


My point was that a society dominated by young men is going to have more crime than a society with a median near middle age - that smaller families made us calmer. They didn't convince me that younger parents are worse than older ones.


It is probably more accurate that allowing unwanted children to be aborted resulted in the drop of crime 20 years later than the removal of lead. This was mentioned in Freakonomics the movie as yukichan linked.


Yeah except that is 1 datapoint cherry picked vs. the wealth of evidence across national borders that leaded petrol was to blame.


Maybe there is an interesting story to be written concerning another heavy metal - mercury and its use in dental amalgam.

Aside from whether it's prudent - irrespective of current evidence - to permanently store a compound containing 50% of a neurotoxin an inch or two from your brain, the release of almost 3,000 kilograms (6,613 lbs.) of mercury (data for 2005 alone) into the atmosphere from crematoria is cause for worry. Wikipedia notes that 'Good empirical data on the magnitude of mercury emissions from crematoria, however, are lacking'. No one is interested I guess.


This is relevant. Always use cold water from your pipes to cook with and drink especially if you live in an older home. Also let the water run for a minute to flush out the pipes if it hasn't been used in a while.

The EPA states:

>Flush your pipes before drinking, and only use cold water for consumption. The more time water has been sitting in your home's pipes, the more lead it may contain. Anytime the water in a particular faucet has not been used for six hours or longer, "flush" your cold-water pipes by running the water until it becomes as cold as it will get. This could take as little as five to thirty seconds if there has been recent heavy water use such as showering or toilet flushing. Otherwise, it could take two minutes or longer. Your water utility will inform you if longer flushing times are needed to respond to local conditions.

>Use only water from the cold-water tap for drinking, cooking, and especially for making baby formula. Hot water is likely to contain higher levels of lead. The two actions recommended above are very important to the health of your family. They will probably be effective in reducing lead levels because most of the lead in household water usually comes from the plumbing in your house, not from the local water supply.

http://skeptics.stackexchange.com/questions/8615/is-there-an...

http://www.nytimes.com/2008/01/29/health/29real.html?_r=0


It's significant that there is this advice, and it supports the point of the article, but this is really insufficient. If you can't be sure of the water quality at the tap (as parent notes, different from the quality at the plant where the utility measures contaminant levels), then it's best to use a filter that removes metals (as well as biological contaminants).

Also people should be aware: the government somehow allows pipes and fittings to be sold as "lead free" when in reality they contain up to a few percent of lead.


Be careful with filters-the main issue with lead is that it leaches from pipes and/or solder. Most of the cases I am aware of in modern (post 1970s) US homes were related to whole house reverse osmosis systems, because the ion-free water had so much more capacity for free metal ions. If you have hard water, it is almost impossible to persuade lead out of the pipe into solution. If you do want to use a filter, make sure you have an at the tap point filter as well.


The European Union (EU) banned lead from petrol in 2000. [1]

Airplanes are still allowed to used leaded petrol!! [1]

And the immigration movement to Europe increased the crime. [2]

[1] http://de.wikipedia.org/wiki/Motorenbenzin#Verbleites_Benzin

[2] http://en.wikipedia.org/wiki/Immigration_to_Europe


Scott Alexander had a pretty good blog post on other sorts of potential biological correlates with crime recently.

http://slatestarcodex.com/2014/02/18/proposed-biological-exp...


I ate lead paint chips I turned out fine... None of those felony charges stuck.

http://en.wikipedia.org/wiki/Buckeye_CableSystem

I don't doubt that the reduction of lead in our environment has reduced the amount of mental illness. But I also think changes to truancy laws in the US in the 70s helped, advancements in psychotherapies, and drugs for the treatment of mental illness helped. Identification of treatments for ADD and ADHD helped.

Changes in the economy helped, we had more women in the workforce which meant we had more ability for families to survive father's unemployment.

Wider adoption of TV meant people became more aware of crime, and criminals were easier to catch.

So yes, lead removal was probably a contributor, but I think it was bigger than that.


I wonder if the result could be less about the lead itself having a direct effect on behaviour, and the action of the removal of lead being identified as "something obvious and beneficial which would be good to do" as being coincident with a greater enlightenment amongst those making the rules?

I.e. to what extent "we should remove lead from petrol as that is obviously bad" is actually a handy indicator of more considered minds running the shop, those minds also being more predisposed to the kind of other "obviously good" decisions which could also have brought about an eventual reduction in crime.


Sort of related, neat history of another toxic gasoline additive: tetra-ethyl lead

http://www.damninteresting.com/the-ethyl-poisoned-earth/


This is the same additive discussed in the OP


This is a better article than the OP. Thanks.


I see you didn't click through and read the article.


Speaking of toxic, do you think you could be less so? I realize you're a throwaway but you wouldn't need one if you weren't being abusive and rude.


Gracias.

There seem to be ever more folks ready to overreact with pitchforks and cudgels calling for the draw and quarter anyone over misinterpreting the color of a bikeshed.

It's too bad folks choose to disagree, point out something as an excuse to be uncivil and with the cowardice of anonymity.


I grew up in the 90s and can affirm that violence was substantially higher than now. It was common to get into 'street fights' just for something to do. But, I'm also curious whether there were higher death rates for the potentially violent, which could have also rapidly reduced crime rates.

Of my friends in the 80s / 90s, I've had around 20 of them die over the course of 20 years. Of those who've died, I can say the great majority were in the 'violence prone' category. They generally seemed to have lower ability to gauge risks and sought out risky behavior, frequently.


Why all the down votes? HN is becoming a hostile wasteland.


Previous HN discussion a year ago with 200 comments: https://news.ycombinator.com/item?id=5006368


I've never seen a study correlating the rise and ubiquity of video games with the drop in crime.

Before video games, bored young males ran around the neighborhood making mayhem. Today they sit in front of an xbox. I personally think the people who would be out committing violent crimes are still in society they just have a way doing it virtually.


I can't find a link at the moment, but I've seen articles where parents in bad neighborhoods talk about buying their sons video game consoles specifically to keep them sitting at home, rather than out on the dangerous streets.


An enlightening article, it reminded me of an article from the Guardian on ammonia synthesis and its environmental and social impact:

http://www.theguardian.com/science/2013/nov/03/fritz-haber-f...


Is there anything new in this article? There was another piece that I think I remember reading on HN about a year ago on this same topic.

http://www.motherjones.com/environment/2013/01/lead-crime-li...


Might be able to confirm this by testing kids for lead poisoning in countries where leaded gas is still legal.

There are children that lived in the country and later move to the city. How early their exposure began would be the variable being tested.

You could treat all cases of lead poisoning you find and still be able to measure the impact of leaded gas on development.

Of course, I think the jury has been in on lead gas and paint for decades. But I guess for a poor country, an economic case must be made.


Well, it's talking about chronic lead poisoning, not acute lead poisoning. Different things. It's interesting to consider that chronic lead poisoning could have escaped notice for a long time because the symptoms seemed like random variance to you or me when they were actually a trend.


Does anyone think there could also be a link between lead in fuel and Alzheimer's? If there was, at what point would we start seeing Alzheimer's cause decline?


Are there countries, or locations in the USA that could be used as a control for this hypothesis? Places that didn't get rid of lead.


The control is Australia, which got rid of it about a decade later than the US.


South Africa only phased it out completely in 2006: http://www.southafrica.info/services/consumer/clean_fuel0812...


Are there places that still use it?


Wikipedia says it is still available in "Algeria, Iraq, Yemen, Myanmar, North Korea, and possibly Afghanistan."


also Iran


There are places that got rid of lead much later than others, they also showed a corresponding later decline in crime levels. What's even more interesting is that the decline occurs regardless of criminal policy (eg. zero tolerance or rehabilitation, shorter/longer sentences).


I think there are still places that are within the 20 year window of the abolishment of lead, but they'd be disappearing pretty fast. Since we can probably assume that there is no place in the world that will or would indefinitely allow the use of lead in gasoline (and if they would, obtaining meaningful crime reporting numbers out of them might be tricky), comparing the time lag across jurisdictions is the best control we'll probably get.


The incredible thing is that they still allow private aviators to use leaded gas, primarily because it would cost the owners of obsolete aircraft a few thousands dollars to either refit their engines, or get supplemental type certificates for unleaded gas. These joyriding dipshits fly all over the place spraying lead over everybody.


Getting rid of lead in gasoline is important because we consume a LOT of gasoline. We don't consume nearly so much Avgas -- it's about three orders of magnitude difference and as such it's a drastically smaller pollution source: http://en.wikipedia.org/wiki/Avgas#Consumption

If you're truly concerned about lead in the environment you'd be best served going after old structures with leaded paint -- not Avgas.


And yet avgas is still responsible for nearly half of lead emissions in the US now. That seems significant.


Only if the lead emissions as a whole are significant.


True, but from what I can see, research indicates that it is.


Only because lead paint is excluded from your statement by definition. It's already "emitted."


What proportion of atmospheric lead comes from lead paint?


Old structures with leaded paint don't routinely spray it in a fine mist of particulates from several thousand feet in the air, do they?

Do I understand correctly that leaded paint is harmless until scratched or otherwise dispersed?


Lead paint can get pulverized and dispersed as dust as you open and close windows and doors and the like.


As a "joyriding dipshit," I can assure you we're not spraying you with lead. General Aviation is moving away from leaded fuel in general. In fact, Shell recently announced an unleaded alternative to AvGas that can be used in a normal engine without issue. No new equipment required.

http://www.aopa.org/News-and-Video/All-News/2013/December/3/...


That's wonderful, but get back to me when the FAA (or the EPA) actually outlaws 100LL. Offering unleaded gas at airfields, even if that happens, won't solve the problem of people using leaded gas. Hell, there isn't even an FBO anywhere around where I live that offers an autogas pump. It's 100LL or JetA or nothing.


They are planning the transition right now. 2018 is the goal for phase-out.

http://www.networkworld.com/community/blog/faa-wants-all-air...


Even more incredible is that our parents and grandparents willingly drove cars that spewed out lead into the atmosphere.

They knew lead was a poison.

Even the Romans knew lead was a poison so it wasn't like asbestos where suddenly a realisation was made.

Yet everyone pretended it did not matter. Everyone did what everyone else did. Nobody thought to avoid driving past schools because they weren't sure about the ethics of covering kids in a cloud of lead (with NO2, CO, O3, PAH's and maybe some invisible micro particles thrown into the mix).


Many people still drive around cars that spew toxins into the atmosphere.

Air pollution from cars kills 50,000 a year in the UK [0]. Apparently closer to 200,000 a year in the US.

But it's even worse than that. 1.24 million each year are killed directly by motorists.[1] There are more young people killed directly by motorists than malaria or aids.

And yet many people are happy to continue driving around.

It's not like this is unavoidable. Electric cars are here, we could move the pollution out of cities. We could design our cities to be safer for walking and cycling. We could invest in public transport and pass on the cost of some of the externalities of cars to motorists.

[0] http://www.theguardian.com/environment/2010/mar/22/air-pollu... [1] http://www.who.int/mediacentre/factsheets/fs358/en/


I don't know how it is where you live, but I pay about 60% tax on gas. This is quite common in Europe. How much more of the externalities do you want to burden drivers with?


Enough to make them drive less!


> Air pollution from cars kills 50,000 a year in the UK [0]. Apparently closer to 200,000 a year in the US.

So just to be clear... you're complaining that the US has five times the population of the UK but four times the deaths from air pollution?


I don't think it's that people pretended it didn't matter. They intentionally sited the pollution in neighborhoods full of Those Other People. Take, as an example, my town of Oakland, California. Are there freeways all over West Oakland? You bet. Are there freeways in Piedmont? Of course not. Rich people have historically been pretty careful to keep the freeways out of their neighborhoods. Airborne lead doesn't get very far from the freeway before it hits the ground.

Your overall point is right, though, that mid-20th-century motorist pretty much behaved like an oblivious jerk for decades.


> "Rich people have historically been pretty careful to keep the freeways out of their neighborhoods."

You're saying that had something to do with fear of lead poisoning?


More likely with general fear/dislike of air pollution combined with dislike of noise and high traffic itself. Living close to freeway is unpleasant, rich can afford something else, poor can not. Where it is not about about direct money, it is usually rich not poor who make decisions.


While today it is largely a question of where one chooses, and can afford, to buy or rent, the freeways haven't been here forever. They were built within the last several generations, and always located so that they would destroy the livability of lower-class neighborhoods. The freeway concept is inherently unjust; it doesn't merely reflect the injustice of society.


There were and are lots of reasons for not wanting freeways in ones neighborhoods, the exhaust is only one of them.


Our parents and grandparents were the joyriding dipshits.


You certainly seem to hate general aviation!

AV gas is being replaced step by step but since leaded gas has its advantages, the replacement process takes time – and there is no really convincing alternative. Anyway, the amount of lead is probably no significant factor in air pollution, there is simply not enough general aviator flying for that.


I don't hate general aviation at all. But I do hate the segment of the AOPA who are basically an offshoot of the NRA, the 100LL-from-our-cold-dead-hands faction. It sounds like you are an aviator so you must be familiar with the people I am talking about.

It's true that if you average the consumption of avgas over the service of the planet you get a pretty small number, but that's no consolation to the family at the end of the airfield who actually gets all of that stuff deposited in their back yard.


I think you're probably a troll, but I'll bite anyway:

I've been active in general aviation for years, and I've never met one these pro-lead strawmen you write about. Since you seem to have all the answers, can you put forward a rational solution to the problem (that isn't "Just throw away all the airplanes")?


How was it handled with cars? At some point, leaded gasoline became unavailable for cars. And yet, cars from before are still around, apparently limited by maintenance and accidents rather than fuel. How was that handled?


New cars were mandated to use unleaded fuel. As demand for leaded fuel dropped off, it became uneconomical for fuel retailers to keep a separate tank and pump for leaded fuel. There may have been (probably was) a hard cut-off date for sale of leaded motor vehicle fuel as well.

The older cars that were originally designed for leaded fuel were either retrofitted with hardened valve seats that didn't require the lubrication of lead, were simply run on unleaded to their deaths, or in some cases (Mercedes-Benz comes to mind, though there may have been others) never needed lead to begin with.


If the engines can be retrofitted to work on unleaded gas, that seems like the obvious way forward for the general aviation fleet, then.

I'm sure it won't be cheap. And this isn't just an abstract cost to me; although it won't hit me nearly as hard as some, I do belong to a flying club which owns two airplanes that would need the work. On the other hand, owning an airplane is painfully expensive anyway. Perhaps I'm off base, but it sounds like the unleaded retrofit wouldn't be too painfully expensive when, say, combined with a 2000-hour overhaul.

I'm sure there will be a number of aircraft owners who couldn't afford it and would have to sell their plane at a discount once the fuel cut over. I'd feel bad for them. On the other hand, they (we) are running pretty dirty machines that emit some nasty pollution, and it shouldn't be a big surprise that they (we) can't get away with that forever.

On one hand, the small size of the GA fleet means that this is a tiny problem compared to leaded gas use in cars. On the other hand, the general reduction in pollution in the US means that it's substantial relative to what's left. Leaded fuel used by GA accounts for almost half of all lead emissions in the country now, and that seems worth fixing.


As a GA pilot, I cringe everytime I gas up and spill a little on myself or on the ground. That lead can't get out fast enough!

But it is also incorrect to draw a parallel to cars, because there was enough volume for cars to transition gently to unleaded gas; you could get both for a while. There is not enough volume of 100LL for FBOs to have two tanks, so, the switchover will have to be all at once. That's why the "drop-in replacement fuel" search is going on... Don't know if it will come to fruition, but if it does, sure makes the problem a lot easier.

Today, though, it's frustrating to have an airplane that I know could run fine on ethanol-free, lead-free 92 octane motor gas, but am required by law (unless I buy an STC) and by practicality (what airports sell) to use leaded fuel.


The transition period would be painful. Seems like the way to go would be to mandate the end of 100LL, but make it perhaps five years in advance, or more. Could mandate that unleaded conversions be done for continued airworthiness sometime in advance of that date if that would help things along.

I guess I'm assuming that an engine that's been converted for unleaded will still work on 100LL. Obviously that's the case for yours, but I suppose it may not be the case for all. If so, that would complicate things severely.


The problem is that many engines can't be retrofitted to work on (premium autogas) unleaded gasoline.

Most normally aspirated engines will work fine (in some cases, better) on a high grade unleaded auto gas.

Most turbo-charged engines lack sufficient detonation margin when run with that "premium" auto fuel, and need some form of octane boost to provide adequate detonation margins for a high-temp, max performance takeoff run. Several groups, including Swift, GAMI, and Shell, are working on drop-in zero-lead replacements for 100LL. All are flying the fuel in experimental applications as I understand it. None appear "close" to certification.

The real problem is that the bulk of gallons burned are burned by airplanes that are turbo-charged. So, even if 75% of the engines can be readily converted (in many cases, a paperwork-only STC), those 75% of airplanes likely represent fewer than 25% of the gallons burned.

I've been to GAMI in Ada, OK and seen them run their no-lead fuel in a lab setup. It's impressive and looks like it would work. They still face a steep and long uphill battle with the FAA, as do Swift, Shell and the others...


There was one more solution employed in various places: aftermarket additives. These could be actual leaded additives, or more likely some substitute which would somewhat reduce wear on valve seats. These additives were not commonly used in cars in the US, but were/are commonly used in other countries where leaded gas disappeared faster than old cars, as well as in the US itself in farm and garden tractors, whose engines often last multiple decades.

Perhaps we could do the same for small planes, but clearly it would take a lot of research and testing to make sure it's safe. If someone is willing to pay for that testing, it's probably doable.


45 years isn't long enough?


At $6/gal you can be sure we're not spraying a lot of it.

-- signed: Joyriding Dipshit

(jealousy is an ugly, ugly thing...)


funny, i was just speaking with someone this weekend who was convinced about correlation to crime in NYC vs legalized abortion. (Donohue-Levitt hypothesis) http://en.wikipedia.org/wiki/Legalized_abortion_and_crime_ef...


I'm a target shooter, I wonder how the lead contained in the bullets and that is burned at firing time is affecting me :s


This was a concern for the armed forces who have conducted studies on lead-alternatives for ammunition. (Aplogies if I get my bullet terminology wrong - I have little idea about this stuff. Here I'm talking about the lead slug projectile part of the round of ammunition).

http://m.bbc.co.uk/news/magazine-19116438

I think that alternatives cause other problems by stripping the gun barrel and etc.

On a gentle tangent I sometimes wonder how many rounds of ammunition were fired during Iraq and Afghanistan wars. And how much brass and lead there is for local populations to recover and sell. And whether that's worth the risk of handling unfored ammunition or finding cluster bomblets or similar.


The brass would be more easily recovered. The lead and depleted uranium is not quite so simply recycled.

Recall that hollow-point ammunition is banned for use by national armies. A lot of their munitions are designed to tumble in soft tissue or to shatter on impact. Some rounds are intended to send a rivulet of liquified metal through armor.

Under such conditions, I am sure that a lot of the fired rounds ended up as dust, to either be inhaled immediately or to become a soil contaminant later. Turning every battle site into a Superfund-style cleanup is unlikely according to the local economics.


If I shot a lot, I would be concerned: http://www.ncbi.nlm.nih.gov/pubmed/19395342

I use lead-free pellets in a pellet rifle, which we keep on hand to shoot at animals that want to eat our chickens. It seems like a lot more pellets are lead-free now than just a few years ago. I don't like the idea of lead pellets laying around on my property. Most lead-free pellets also claim to be "high velocity' so it seems unlikely they are wearing the rifle barrel more than lead pellets.


No. It's mostly due to the big increase in standards of living over the past 40 years. But the BBC don't want to admit that things have actually improved quite a lot because it conflicts with the narrative they try to push day after day so it must be...petrol.



Many variables share this exact graph shape over the 1960-2000 period, without having anything to do with crime. It's not a particularly characteristic shape. This seems to be a textbook example of "correlation does not imply causation".

If there was causation (due to the neurological effects of long-term lead exposure during childhood years), then you would observe delayed correlation (at a 20 year scale), not simultaneous correlation.


Correlation does not imply causation, however correlation can be used to support a theory of causation. The article does address this point:

   "There is a substantial causal relationship," she says.
   "I can see it in the state-to-state variations. States
   that experienced particularly early or particularly sharp
   declines in lead experienced particularly early or 
   particularly sharp declines in violent crime 20 years later."
Without reading the paper, I will not venture any opinion on the hypothesis/research/etc itself. I do however thing it may take more than 5 words to completely dismiss the theory.


The causative mechanism is the body of research done on the brains of criminals. We usually find reduced function or actual damage in the frontal cortex, and other regions associated with empathy and emotional processing.

The other group of people we find this in is those suffering from childhood lead exposure, and we know that the regions of the brain most affected are those which occur from lead exposure.

While not going so far as to imply everyone with this pattern becomes a criminal, it certainly increases the statistical likelihood that they are, and studies on people with extreme issues - i.e. psychopaths - tend to show that's its a pattern of life experiences which determine whether you learn to function in society, or go another path. Notable is the neuroscientist who was studying psychopaths and discovered he has the same sort of brain structure as one - but, is a scientist, married and has children.

Since we can't really control an individuals life experiences through policy, but they roughly sort out statistically based on socioeconomic status, it seems pretty clear that exposure to brain development inhibiting neurotoxins is going to give you a higher then expected fraction of criminally-inclined young adults.


Not that I disagree with you, but the graph in the article is adjusted 23 years between the two lines.


Indeed, that had escaped me. It makes the case stronger then.


The other part that makes it stronger than simple line-fitting is the idea that it tracks similarily, but from different starting points, in jurisdictions where the use of lead started declining at different points. Especially when the jurisdictions pursued similar crime policy at around the same time (ie. the UK and the US).


This always amuses me. Crime in the US was rising... until the mid-90s when the twin powers of the ridiculously high incarceration rate j-curved and the internet bringing all sorts of indoor distractions happened.

I mean, who would have thought that teenage delinquency would be reduced by distributing computer games, giving them something to do rather than wander the streets being bored?

And if lead really is responsible for 90% of the crime, as stated in the article by the chief propagandist, then before leaded fuel was around, crime should have been negligible - and it clearly wasn't.

Edit: perhaps the lead-in-your-fuel people should debate against the concealed-carry people, since both of them claim absolute ownership of the decline in US crime from the mid-90s onwards.


Problem with the CC argument is that this trend has been witnessed in other countries that have no such gun laws. And if the US was a special case, how would it explain all the cities that saw a drop in crime with restrictive gun laws (Several of which were deemed unconstitutional a decade after the crime drop began?)

As for youth distractions: The internet did not have significant saturation until the 00s. http://en.wikipedia.org/wiki/Internet_in_the_United_States seems to indicate that in 2000, only 2.5% of Internet users had broadband.

Video games exploded in popularity in the 1980s while crime was still rising - not to mention this was a time when arcades were far more prolific, so you could make the argument that entertainment was more accessible to youths with families that couldn't afford video game systems in 1980 than 1990 onward.


Going out to an arcade puts you out and about. And when the money runs out, the arcade has no further interest for you. There's no money to run out with a video game at home. While there were some homes with consoles and computers in the 80s, home computers didn't really take off for the general public until the 90s, and you see also that it was the 90s when the game industry at home really took off. You don't need the internet to play video games.

As for CC, it should be clear I'm not fond of their arguments :)


I want to believe but...

Looking at crime stats by age and gender of arrest [1] You see an across-the-board decline for men and women. You're telling me a 60 year old woman was too busy playing Doom on a 486 to commit a violent crime?

[1] http://www.fbi.gov/about-us/cjis/ucr/additional-ucr-publicat...


So, keeping in context of my original comment, do you have statistics for how many 60-year-old women are engaged in teenage delinquency?

Keep in mind that the period you're talking about in the US (1993+) is around the start of hysterical anti-crime politicking, with a soaring incarceration rate, and heavily increased funding for policing.

Or for something more relevant to 60-year-old women in the 90s, how about it being more socially acceptable to leave an abusive husband? Or better social support services than previously?

There's a lot of different things that affect crime - I'm not saying in the slightest that any one thing is responsible for crime or lack thereof.


Actually, the trend appears to be that it was dropping since the late seventies, but had a small upswing in the early nineties before dropping substantially more.


The answer is that criminology is affected by a wide variety of factors, and making statements like the guy in the article that 90% of crime can be attributed to one factor is nonsense.


> making statements like the guy in the article that 90% of crime can be attributed to one factor is nonsense.

And yet, the r^2s when you plug in your data for lead exposure are really high. Odd how that works.


I've mentioned elsewhere a plausible third factor that drives both, and that the data for Australia does not match this pattern. And that I'd like to see this European data that apparently matches it - the linked papers in the article do not mention it.

It's far from the ironclad causative link that you're implying.


> making statements like the guy in the article that 90% of crime can be attributed to one factor is nonsense.

> I've mentioned elsewhere a plausible third factor that drives both

You see the problem here? You claim that a factor being able to drive that much is nonsense, and then you... claim to have identified another factor which drives that much (of both lead and crime).


No, that's you putting words in my mouth. I mean, your first reply to my commentary was specifically against me saying that there are multiple factors in criminology.

Yes, you can argue that because I said 'a factor that drives both' that I meant only one single ironclad factor, but in the context of all that I've written, it's clear that I'm talking about a range of changes - including, again, my comment that elicited your first response, where I explicitly point out multiple factors affect criminology. My first comment in this thread (the heavily downvoted one up there) pointed out two other factors that have been attributed to the decrease in crime as well.

I've also presented graphs of Australian violent crime that don't appear to follow trends in each other, let alone the supposed 'lead-free' crime reduction that this theory presents.

Exactly how many different factors do I have to present to potentially explain variability? To suggest that it's more than one factor that has a significant effect on crime?

Edit: I should probably also point out that the "a" factor I mentioned isn't a single thing that can be measured with a single number like "atmospheric lead", but a suite of many different things dealing with a wide-ranging cultural change (see response to DanBC below)


> I mean, your first reply to my commentary was specifically against me saying that there are multiple factors in criminology.

No, my first reply was that there very clearly was a high fit to the data, and so something is going on that is in need of explanation, be it lead or another confounding factor, and so it was nonsense to claim that it was nonsense that a single factor could matter.

> I've also presented graphs of Australian violent crime that don't appear to follow trends in each other, let alone the supposed 'lead-free' crime reduction that this theory presents.

I don't see any links, so you haven't presented anything. Here, have some graphs of preschool lead vs lagged crime in Australia: http://mpra.ub.uni-muenchen.de/35338/1/MPRA_paper_35338.pdf

> Exactly how many different factors do I have to present to potentially explain variability? To suggest that it's more than one factor that has a significant effect on crime?

You should present something. Otherwise you're engaged in know-nothingism: 'it could be something else! who knows? whoooo knooowwwwssssss...'


Actually, thinking about it further, It's funny that in none of these articles is the point put forward that the kind of people who would want to better educated themselves about and eliminate poisons for the better welfare of their family might also be the kind of people who would try to raise and socialise their kids in a better manner. Lead was removed from petrol at a time of massive upheaval in the way the public looked at raising their kids. This argument would suggest that both reduced lead in petrol and 20-year-later-lowered-crime are both sourced from improved parenting and social actions.


> Lead was removed from petrol at a time of massive upheaval in the way the public looked at raising their kids.

Okay; now did that public view also change per-state, and per-country, tracking the date ranges that lead was removed?

The crime rates track when lead was added/removed regionally, not just generally.


The papers linked in the article don't actually say that, and I'd like to see the papers that do - have you a link to them?

And is it so hard to think that the more progressive regions might do several things earlier than the less progressive regions? I'm not saying this is the actual mechanism at play, just that it's a plausible mechanism that is causal for both trends - something that's always overlooked in thees articles.

Anyway, I spent an hour looking at crime graphs for Australia this afternoon, and I can't see a common pattern at all. Australia banned leaded fuel in 1986 and it was completely phased out by 2000. But the crime graphs are all over the place. Homicide is stable-but-downward. Assualts are rising. Robbery has been both up and down. If lead is the 'silver bullet' against violent crime 20 years later, why the increase in assaults? I just don't see the preliminary patterns required for this "causation" to work.

http://www.aic.gov.au/statistics.html


Could you describe this massive upheaval in the way people raise their children? How is it different from, for example, Dr Spock's book and similar?


The 60s and 70s were a time of massive social upheaval, and people came out of it with a better understanding of how to see other people by merit rather than by tradition. The "Think of the Children!" political slogan rose to prominence in the 70s. This is also the time of better rights for minorities, first wave feminism, and the rise of the phenomenon of questioning authority. Kids raised under the hippy ethos (and related) were far more common than in the 50s. The environments they grew up in had more equality and diversity measures from the civil rights movements. Not perfect, but certainly significant change.


Correlation is not causation. Of course, there is a correlation between pollution and "depression" (as in "depressive regions") or "desperation", but it is not a direct cause of seemed decline in crime.

My bet is that the decline (or at least shift to less dramatic "technological/financial" crimes) is a cultural phenomena, influenced heavily by cheap and easy credit and media (especially so-called "social media"). It is just not cool or fashionable to be a dumb looter or a "primitive" gangster anymore.

Nowadays one has to be "a clever guy" - a cheater instead of a criminal, an internet tycoon, overcharging credit cards of idiots who had ordered a colon cleanser form a stupid website, instead of simple armed robber of a drugstore on the corner.

This works even for Russia, which, putting aside some African extremes, is the most criminalized society in the world. Even for them it is more fashionable to run a porn studio to sell pictures in the net than robbing trucks or brutally killing each other for a used BMW car.

Nowadays one has to be "clever" to steal from the government, to gamble the corrupted [banking] system , cheat on idiots in internet, and even with their own credits and mortgages.

The shift from stupid brutality to technological/financial/social "cleverness" (as they think of it) is what others call "decline in crime".)


Removing lead also lead to greater usage of facebook! Look at the stats!

Lead Usage:

   |\
   | \
   |  \
   -----
Facebook usage:

   |  /
   | /
   |/
   -----
EDIT: While my post is satirical, and slightly obnoxious, it presents about as much evidence and citation as the article. The graph he presents (where did that come from?) doesn't even show proper correlation, it just kinda-sort-of fits.


First off, this is a news article - not a peer-reviewed study. You can't reasonably expect complete detail to be included - have a look at the linked papers.

Second, there's substantially more detail in here than you have stated. For example, the correlation between the decrease in violent crime and the use of lead is reproduced in areas with differing crime policy, and shows a similar kind of decline in areas which stopped using lead earlier or later than others.

Third, "it just kinda-sort-of fits" is all you will ever get in anything outside of pure mathematics. The real world is pretty noisy, and exact correlation is never going to happen.


http://en.wikipedia.org/wiki/Betteridge's_law_of_headlines

"Any headline which ends in a question mark can be answered by the word no."


Betteridge's Law of Headlines is not always true. You can demonstrate this by constructing the headline "Is Betteridge's Law of Headlines always true?"

If the law is always true, then the answer to that headline is "Yes", even though the law dictates that the answer must be "No." This is paradoxical. However if the law is not always true, then the answer to the headline is "No". This invokes no paradox.


I do not think this is a constructive comment. What was the point of submitting this comment?


Careful, they're out in droves downvoting anyone that disagrees with the premise of this story.


We don't need Betteridge's Law quoted every single time there's a question mark in the article title.


We also don't need environmentalist drivel that has no hope of being scientifically proven on the front page of HN, along with a vocal minority waiting to pounce on anyone that questions the validity of such nonsense. Yet, somehow it winds up there.


I'm sure you have at least as much research and data backing your hypothesis as this article does. Please do link it so we can take a look for ourselves.

I'm sure you don't just have an unreasoning, politically-motivated, knee-jerk hatred of anything that strikes you as "environmentalist." That would be silly, after all.


That's just it: this article presents no data showing a definitive link between the two. Show me some evidence of that, and I'll be happy to agree with it. I agree with facts; not politically motivated opinions. It shows that one thing happened, and another thing happened. The tie (or, the much hated term "correlation") between the two is a stretch at best.


See comments elsewhere about the effects observed when lead was removed from gasoline in different geographical areas at different times. The correlation is strong enough to be suggestive of a causal link -- so strong, in fact, that the burden of proof lies on those (e.g., yourself) who claim that there is no causal link.


I downvoted you. I didn't downvote you because you disagree with the article, but because your comments are empty dismissals of the headline without addressing the points in the article.

I also downvote anyone who mentions betteridge if they don't make any other point. Comments like those are toxic and pointless. They add nothing to any discussion. We know that headlines are usually stupid and misleading and link baity. Ignore headlines. Read the article and talk about that instead.


> I downvoted you.

Join the club. I have lost 54 points so far in this single thread. The radical environmentalists seem to be upset with me. I actually don't care though, because whenever I see politically-motivated opinions masquerading as (junk) science, and otherwise intelligent people lending credence to it, I am going to say it.

The article's main thrust is not remotely provable, but is easily disprovable. That is all I have said. There you go, now downvote me. Let's make it an even -55 points.


You keep using terms like "radical environmentalists". Most of HN are not in any way "radical" in terms of environmentalism. That alone is going to attract downvotes.

You say that the article is easy to disprove, yet you have made no attempt to do so.

Attmepting to have a discussion might have got you less downvotes than merely saying "this article is wrong".


I don't care about the downvotes. The article did not prove its basic premise. It's that simple. I will keep saying it and keep getting downvotes.

There aren't a lot of radical environmentalists on here, but I have several comments in this thread. Each one that is here can go through and take several points away, they've been doing it all night, and are apparently telling their tree hugging friends to do it as well. It's rather telling that all of my comments have -4 points; 5 crazies have taken 60 or so points. All it shows is that HN isn't the place it used to be.


'they'?


That graph seems silly, why use two different time scales?


They're showing it roughly twenty years later. The argument being, in effect, that lead exposure when young lead to later-life criminal behaviour.


Oops, now I feel silly :) Thanks.


I think the idea is that lead exposure in childhood leads to crime later in life


Correlation does not imply causation. While lead exposure may have something to do with it, an issue like the crime rate is driven by a number of complex factors.

Perfect example of why this type of analysis is ridiculous:

http://en.wikipedia.org/wiki/Super_Bowl_indicator


You might enjoy this article: "Correlation does not imply causation: How the Internet fell in love with a stats-class cliché"

http://www.slate.com/articles/health_and_science/science/201...


That comment was such an epic burn, it contributed to global warming!

... Which is why, I suspect, the commenter you replied to won't believe it either. Sigh.


Cliche or not, in this case and many other cases, it remains true.


This is not a meaningful contribution to the conversation. If you'd read the comments and replies made before you posted perhaps you'd have been able to contribute something other than the trite "correlation does not imply causation" which may just be the most obnoxious phrase on the internet today.


I strongly disagree with the article for one reason: Correlation does not imply causation. That is what I said. I realize that my comment flies in the face of the opinion of radical environmentalists. Does that make my opinion invalid?


I think this post explains it without me repeating someone's words.

https://news.ycombinator.com/item?id=7619054

Your "contribution" of repeating the phrase doesn't educate anybody, doesn't address the actual content of the article. It doesn't make your opinion invalid but it also doesn't contribute anything meaningful to the understanding of the article. It was also said several times before you deigned to enter the conversation and "educate" us about correlation.


It doesn't address the content of the article? Apparently you did not read the article. It specifically is trying to say that the correlation between crime rate and removal of lead from gasoline is attributable to it (e.g. caused by it). I strongly disagree with it. That's what I said.


There's plenty of more strongly correlated suggestions for the drop in crime than TEL: legalized abortion, drug trends, law enforcement, on and on. Common sense would put TEL at hypothesized causation reason # 10 or so.


There's a strange battle going on in this discussion, but honestly -- I dismiss a lot of quasi-scientific articles that put a lot of importance on correlation without addressing a ton of alternate explanations.

This one, I can't dismiss so easily; I've read into the details of where this theory comes from via a few sources, and the correlations are rather more than just "this line goes up & then down where this other line also goes up & down".

I'd suggest the naysayers read into this one a bit more before dismissing it (though I do understand the reaction).


  Does that make my opinion invalid?
Do opinions become somehow more correct just because they are contrary to the 'popular' view? Statements like:

  I realize that my comment flies in the face of
  the opinion of radical environmentalists.
are not part of a constructive conversation. Did the parent post claim to be a radical environmentalist? Are you trying to passive-aggressively claim that the poster is a radical environmentalist? If neither of these are true, then what was the point of that statement?


Since my objection to the very premise of the article (that premise being that a reduction in environmental exposure to lead caused a drop in crime rates) seems to be his primary objection to my comment, yes, I am saying he or she is quite invested in radical environmentalism.


I don't care much about this article, but I'm reminded of pg's middlebrow dismissal comment.


Correlation does imply causation. It does not guarantee causation.


Also, in this case, we have multiple cases of correlations. Throwing three sixes in a row wit a die isn't evidence that a die is loaded, but doing that 10 times out of 20 attempts? Highly suspicious.

Of course, with a die, we can weigh it, find its center of gravity, cut it poem, etc. that makes it easier to 'prove' what's the cause of our extraordinary luck.

Bu suppose we find that the die contains some mechanism that allows one to change its center of gravity. Then, we cannot be sure that all those '3 sixes in a row' throws were caused by a change in the center of gravity.

Here, the case is more difficult, because we cannot cut open the object of study.


Nitpick: throwing three sixes in a row is absolutely evidence that the die is loaded. It's not proof, but it's definitely evidence.


Correlation does imply causation, it just doesn't prove it.

Multiple correlations over different data sets, in the presence of an extremely plausible mechanism - we know for a fact what lead exposure does to developing brains - is as close as we ever really get to proving a causative link in this world.


> Correlation does not imply causation.

Okay, accepting that as a working assumption for the argument: What does? It's not things happening together that implies it, it's not things not happening together that implies it - negative and positive correlation respectively - so what is it?

The only other explanation I can think of is an understanding of the underlying mechanism, but what's that understanding based on? It can't be understandings of underlying mechanisms all the way down - you have to acquire the data from observation at some point.


Lead is well understood to be a neurotoxin. There's a clear mechanism of action here.


Some say it was a decline in environmental lead, as the linked article does. Some say it was the advent of mandatory sentencing and three-strikes laws. Some say it was the easy availability of birth control and abortion, meaning fewer unwanted children were born.

But, social psychologists to the contrary, we will never know, because this kind of study can never ascend to the level of science. All we can be sure of is a rise in ... not crime, but contentless articles whose titles end in a question mark.


Antipositivism is a thing, like it or not. I've aways loved the quote from Heisenberg:

    > The positivists have a simple solution: the world must be divided into that
    > which we can say clearly and the rest, which we had better pass over in
    > silence. But can any one conceive of a more pointless philosophy, seeing
    > that what we can say clearly amounts to next to nothing? If we
    > omitted all that is unclear we would probably be left with completely
    > uninteresting and trivial tautologies.
Rejecting the entirety of a science because it deals in confidence values rather than "facts" is foolish; it might be better to judge works based on their quality, rather than some ranking that deems X to be a science and Y to be something other. I particularly love that you used the word "ascend"; I shan't be the first to compare positivism to scientism


> Rejecting the entirety of a science because it deals in confidence values rather than "facts" is foolish ...

I'm not rejecting pop psychology. I'm saying it's not science. Science requires something fundamental, it can be expressed in one word, and I invite the readers of this post to say what it is. As soon as the word leaves their mouths, they will realize why social psychology cannot be science.

When the physicists at the LHC observed what they thought might be the Higgs Boson, they refused to announce a discovery until the had a five sigma result. Five sigma is approximately equal to 2.8 * 10^-7 (explanation: http://blogs.scientificamerican.com/observations/2012/07/17/...), and it expresses the probability that, if there is no Higgs particle, a random observation might create the observation that has been made.

Five sigma. That's science. Opinion articles whose titles end in question marks are not science. And I should not have to explain this to educated readers.

> I particularly love that you used the word "ascend"; I shan't be the first to compare positivism to scientism

Scientism is an irrational confidence in science as an answer to all the world's problems. Social psychology is an irrational confidence in the power of articles that observe correlations without either proposing or testing theories about those correlations to accurately represent some aspect of reality.


"science", to some, implies a discipline subject to the scientific method - none of this discussion is. Replace "science" with "discipline" in your post and it will make sense.


Nope. Still not seeing how "this kind of study can never ascend to the level of discipline (née science)" is something that can be stated without any supporting argument.


I was referring to "science" in your description of "Rejecting the entirety of a science because it deals in confidence values". It does not give confidence values. It is not science in the "scientific method" sense. It is a descriptive discipline, yes, and it can be useful - but it could be a random correlation, or correlated through a hidden variable. An observational study is, scientifically, not a valid way to establish cause and effect.


> Still not seeing how "this kind of study can never ascend to the level of discipline (née science)" is something that can be stated without any supporting argument.

If you understood the basics of science, you would know what's missing from an opinion article that picks a quantity at random and discovers a correlation with something else, but without a testable theory about how they might have something to do with each other.

Science requires something, that something can be expressed in s single word, and once that word is uttered, all who hear it will realize why this kind of article cannot represent science. And I am astonished by how few people know this requirement of scientific practice.

Science isn't the answer to the world's problems, but for certain problems, it has no meaningful substitute.


As a thought experiment, just imagine Max Planck, Werner Heisenberg, and Richard Feynman gathering their teams together in a room for a major announcement.

All three scientists have reached a unanimous conclusion. Each time they try to measure some aspect of an atom, their results are inconsistent! They declare to to their teams that this cannot be real science. After all, we need reliable measurements in order to do science. So let’s not waste our time any longer. Go home, get some rest, and come back tomorrow. And please take a moment to review the equations governing the path of flying baseballs. We think this merits a second look.

Fortunately history tells a different story.

By the way, I’d highly recommend reading the outstanding book “Quantum Mechanics: The Theoretical Minimum” by Leonard Susskind of Stanford. If you’ve seen a matrix before, then you’re good to go (with some effort). He walks you through the rest.

As a fair warning, try to mentally prepare yourself. Your seemingly rational & logical viewpoints, while admirable, will be shattered one by one. And you’ll see that even our precious boolean logic is merely an illusion.

EDIT: Oops. Wrong level. This reply was geared to downandout in above thread. Apologies.


What makes you say that this kind of study can never ascend to the level of science? This kind of study is science. It's imperfect, but all of science is; science is just a collection of tools to improve our knowledge of the world, coupled with the body of knowledge so gained. Some of those tools are stronger than others, or can provide more certainty.

Controlled studies in which you vary only one input to a system at a time, and observe the effect, are obviously a stronger tool than mere observational studies. But that doesn't make observational studies not science.

It's perfectly possible to determine which of these effects are more or less likely to be responsible; the different hypotheses that you make would make easily testable predictions, which can be tested independently because different jurisdictions have made these changes at different times. Lead was banned in different countries at vastly different times (https://en.wikipedia.org/wiki/Tetraethyllead). Likewise, three-strikes laws have been introduced at different times in different places, and many places have never introduced such laws (https://en.wikipedia.org/wiki/Three-strikes_law). Easy availability of birth control and abortion may be a little harder to quantify precisely, but that can be done too.

Since some countries have only banned leaded fuel in the past 10 years, within another 10 or 15 we should be able to say with considerably more certainty whether this has a causal relationship. If the crime data for countries which banned it later follow the same pattern, that's a very strong indication that the theory is correct.

I would find it hard to believe that the three strikes laws would have the same effect, as the reduction in crime has been happening fairly consistently nation-wide, while three strikes laws have been implemented at vastly different times in different states, or not at all. Lead levels are much more consistent nationwide, as those have mostly been national laws (with the exception of California banning leaded gasoline a few years earlier).

Anyhow, I strongly disagree that you can say that this isn't science. It's imperfect science; anything as complex as the social phenomenon of global crime levels is going to have a lot of complex, interacting factors and no one of them is going to be completely explanatory, and you are never going to be able to do significant studies with controlled inputs. But there are scientific tools for dealing with these somewhat more ambiguous situations, and we can and should apply them as the policy implications are quite substantial.


> What makes you say that this kind of study can never ascend to the level of science?

Because the uncontrolled nature of the observations means evidence cannot be reliably collected in a way that separates one cause from any number of unintended causes and side effects. The only way to get around these obstacles would be to feed one group of people doses of lead and compare them to another in a controlled setting, or isolate two groups of people, give one group the right to birth control and abortions, deny the other group those rights, and keep them from finding out about each other. Things that cannot be done for ethical reasons, and things that prevent social psychology from rising to the level of science.

This is why social psychology cannot be a science, and it explains why the field has the terrible reputation it has and deserves.

Link: http://chronicle.com/article/As-Dutch-Research-Scandal/12974...

Quote: "Even before the Stapel case broke, a flurry of articles had begun appearing this fall that pointed to supposed systemic flaws in the way psychologists handle data. But one methodological expert, Eric-Jan Wagenmakers, of the University of Amsterdam, added a sociological twist to the statistical debate: Psychology, he argued in a recent blog post and an interview, has become addicted to surprising, counterintuitive findings that catch the news media's eye, and that trend is warping the field."

> Anyhow, I strongly disagree that you can say that this isn't science.

Yes, I understand, but you haven't the slightest idea what makes science science. If you did, you would recognize this sort of article for what it is.

Social psychology deserves its reputation, science operates at a higher level, this is Science 101, and you have no idea what you're talking about. Not a clue.

There is a one-word summary of what science requires, that word is known to every qualified scientist, and you do not know what it is. How do I know this? You defended social psychology for over four hundred words without even mentioning it.


> Because the uncontrolled nature of the observations means evidence cannot be reliably collected in a way that separates one cause from any number of unintended causes and side effects. The only way to get around these obstacles would be to feed one group of people doses of lead and compare them to another in a controlled setting, or isolate two groups of people, give one group the right to birth control and abortions, deny the other group those rights, and keep them from finding out about each other.

Uh, no, statistical controls are a real tool of real science. While laboratory conditions are in some ways (ethics aside) ideal, they aren't a prerequisite for real science.


> Because the uncontrolled nature of the observations means evidence cannot be reliably collected in a way that separates one cause from any number of unintended causes and side effects.

If we couldn't scientifically deal with this scenario, we'd hardly do any science. The world is noisy, measures are inaccurate, life is not perfect, but we learn to deal with it. Not all science can be math theory. When it touches the real world, you have to deal with imperfection.


> If we couldn't scientifically deal with this scenario, we'd hardly do any science.

Feel free to change the topic. Science is very clearly defined, and an absence of falsifiability is fatal.

Either:

1. A theory can potentially be falsified by new evidence, or

2. IT IS NOT SCIENCE.

http://en.wikipedia.org/wiki/Falsifiability

Quote: "The concern with falsifiability gained attention by way of philosopher of science Karl Popper's scientific epistemology "falsificationism". Popper stresses the problem of demarcation—distinguishing the scientific from the unscientific—and makes falsifiability the demarcation criterion, such that what is unfalsifiable is classified as unscientific, and the practice of declaring an unfalsifiable theory to be scientifically true is pseudoscience."

Which part of the above didn't you understand?

> When it touches the real world, you have to deal with imperfection.

As I said, feel free to change the subject.


No need to be rude - you have come to an invalid conclusion here, and it would be better to try to understand why than yell at others.

So, what about this research is not falsifiable?

For example, if research finds another location in which lead additives were not banned, but in which crime declined with the same characteristics as the drop being ascribed to the ban on lead in other countries, that's strong evidence that the theory is indeed false.

In other words, your point is entirely incorrect.


> you have come to an invalid conclusion here ...

It's time to offer evidence, not opinion. My claim (and that of scientific philosophers) is that falsifiability is requires for science. That is not a point that's open to debate, it is an established requirement. It's even written into the law, for example laws that prevent Creationism from being presented as science in public school science classrooms:

http://en.wikipedia.org/wiki/McLean_v._Arkansas

Quote: "The judgment defined the essential characteristics of science as being:

   * It is guided by natural law;
   * It has to be explanatory by reference to natural law;
   * It is testable against the empirical world;
   * Its conclusions are tentative, i.e. are not necessarily the final word; and
   * It is falsifiable."
> So, what about this research is not falsifiable?

Try to imagine how someone could prove false the claim that a reduction of lead in gasoline caused a reduction in the crime rate, to the exclusion of other factors, in a social setting, with no meaningful controls in place.

> In other words, your point is entirely incorrect.

You need to make an argument before coming to a conclusion. At least, that's the rule in a scientific debate.


Try to imagine how someone could prove false the claim that a reduction of lead in gasoline caused a reduction in the crime rate, to the exclusion of other factors, in a social setting, with no meaningful controls in place.

I literally gave you an example of this already, and you've ignored it. I can only assume you're responding in bad faith.


>> Try to imagine how someone could prove false the claim that a reduction of lead in gasoline caused a reduction in the crime rate, to the exclusion of other factors, in a social setting, with no meaningful controls in place.

> I literally gave you an example of this already, and you've ignored it.

You're ignoring the requirement to "prove false". Your example doesn't meet this criterion, and the criterion is required for science. Here's your example:

"For example, if research finds another location in which lead additives were not banned, but in which crime declined with the same characteristics as the drop being ascribed to the ban on lead in other countries, that's strong evidence that the theory is indeed false."

No, that's not "strong evidence", it merely introduces another confounding factor, and it is not remotely a basis for falsification. It's not a black swan.


You're ignoring the requirement to "prove false"

Unless you are claiming that all observational science is, in fact, not science, then this idea is intractable.

For example - cosmology. We can observe the universe. We can't create any meaningful controls when we do so, but we can use the observed data to construct models. If those models fit our observations, then they are accepted. If we find a situation in which the model does not correctly describe a system (i.e. it has been falsified), then we can modify it, or discard it entirely.

One can adopt entirely the same process to research the effects of lead. We can observe that, based on available data, a certain phenomenon occurred. We can use other sources of information to compensate for other possible causes. If there is information available which contradicts that conclusion, then we can discard the model. Like other scientific disciplines, there is never 100% certainty about the validity of a model, however if adequate contradicting evidence can be shown, then it will be shown invalid.

The "black swan" is a simplistic view of falsifiability. When presented with this swan, one can respond "Ah, you are correct. This is a swan, and it is black; my model for swan coloration is invalid." One could also legitimately respond "Ah, you are not correct; this swan is white, and has been exposed to dye which has made it appear to be black." That is to say that falsification is never absolute, and all observations are subject to confounding factors.

Real science rarely falls into clean classification of certainty and uncertainty; there are always confounding factors, and the model of lead's effect on crime is not qualitatively different.


What makes you say the results of these studies are unfalsifiable?


Try to imagine how you would prove false the claim, in a social setting, with multiple factors at work, and no meaningful controls. If I shake a dried gourd over a cold sufferer and he gets better, I can claim to have been the cause of the recovery. And guess what? No one can prove that claim false. The fact the colds are really caused by germs is true and interesting, but it doesn't falsify my claim to have been the cause of the recovery. That's why scientific claims requires a basis for falsification.

And this is more than a philosophical position, it's written into the law:

http://en.wikipedia.org/wiki/McLean_v._Arkansas

Quote: "The judgment defined the essential characteristics of science as being:

   * It is guided by natural law;
   * It has to be explanatory by reference to natural law;
   * It is testable against the empirical world;
   * Its conclusions are tentative, i.e. are not necessarily the final word; and
   * It is falsifiable."


>If I shake a dried gourd over a cold sufferer and he gets better, I can claim to have been the cause of the recovery. And guess what? No one can prove that claim false.

Umm, sure they can? They repeat the experiment (or perform a better one) and don't get the same results. Lack of controls makes for weaker evidence, but it doesn't magically make things unfalsifiable.

And so I ask you again: What makes you say these studies are unfalsifiable?


> Umm, sure they can? They repeat the experiment (or perform a better one) and don't get the same results. Lack of controls makes for weaker evidence, but it doesn't magically make things unfalsifiable.

Yes, in fact, that's exactly what it does. My dried gourd example should have demonstrated why this is so -- I can always claim a correlation with the gourd and the outcome, and without proper experimental controls, that's irrefutable.

My dried gourd example is meant to show the need for experimental controls -- another group that recovers in the same amount of time without benefit of gourd-shaking undermines the claim that the gourd had anything to do with the outcome. But "undermines" doesn't equal "falsified" -- the latter condition requires that we test an explanation, not just an observation.

The method of performing more experiments, gathering more data, decreases the p-value of the outcome, but it cannot turn a hypothesis into a theory until we're testing an explanation rather than measuring an effect. As long as we measure effects without trying to explain them, we're doing an expensive kind of accounting, but not science. Science requires that we try to offer and then test an explanation for what's being observed, and toss the explanations that don't pan out.

The tl;dr: science requires theories.

> And so I ask you again: What makes you say these studies are unfalsifiable?

The problem we're having here involves a definition of terms -- what falsifiable means. More here: http://arachnoid.com/building_science


I thought this argument sounded familiar, and looking at my comment history confirms it. I argued with you about the necessity of an explanation for something to be scientific previously. Clearly you feel strongly about this issue, so I'll make a better attempt to understand your argument this time.

Can you clarify for me exactly what you mean by an "explanation"? The linked article starts to talk about a difference between description and explanation, but then just arbitrarily says that Newton's theory of gravity constitutes an explanation. I don't see how Newton's theory is anything more than a very detailed description.

Why is the hypothesis "There's a magic force called gravity that behaves according to these laws." any more valid than the hypothesis "Stuff falls because magic." Both provide testable predictions, and can be falsified. Indeed one could simply point to the moon and say "that doesn't fall, theory disproven" just as one could point to the unusual orbits, and disprove Newton. I don't see how that makes the hypothesis itself unscientific.


You could I guess define Science as only applying to areas where you can do controlled experiments - but you would thereby eliminate all observational sciences - evolutionary biology, astrophysics, cosmology, etc.

I suspect most people would find that a somewhat extreme position.

Also, fraud is an issue in all fields of Science, so that seems somewhat an unfair issue to introduce.


> but you would thereby eliminate all observational sciences - evolutionary biology, astrophysics, cosmology, etc.

No. Not if an observation leads to a testable, falsifiable theory, if that theory makes new predictions, if the predictions are verified, and if the theory in all its manifestations remains potentially falsifiable by new evidence. Like quantum theory, the best scientific theory we have, a theory that makes many other fields look like stamp collecting, and a theory that relies on observations of real-world phenomena.

As to cosmology, there are a number of cosmological theories based on observation that have led to testable theories, and those theories have survived reality-testing and have made predictions that are later verified in observations, like the recent observations of the CMB that support inflationary theory and led to some recent Nobel Prizes.

> I suspect most people would find that a somewhat extreme position.

Science is not a popularity contest, and it is not politics.

> Also, fraud is an issue in all fields of Science, so that seems somewhat an unfair issue to introduce.

Many people don't understand that some pseudoscientific fields are all fraud, in which case arguing that all fields have some fraud misses the point.


The hypothesis that lead exposure affects early childhood development, and that this leads to higher crime rates does lead to testable predictions - it predicts, for example, that different regions that removed lead at different times would see crime rates drop at different times. And indeed, this is exactly what we see. Is this as strong as exposing a test population and comparing it to a control? No. But neither is it meaningless pseudo-science.

This line of argument is actually very similar to the cosmological example - the theory makes a prediction about something you should observe, if the theory is correct. However, this is still much weaker proof than being able to generate a Big Bang in the lab and examine the outcome.

The QM case is an example of how much more powerful it is in fields where we can do controlled experiments, I agree. But not everything worth investigating (and worth knowing) is amenable to that type of study.


> The hypothesis that lead exposure affects early childhood development, and that this leads to higher crime rates does lead to testable predictions ...

Yes, but not falsifiability, required for science. Okay, I see people aren't getting this, so here's a classic example. Let's say I am a doctor who believes he has found a cure for the common cold. My cure is to shake a dried gourd over the cold sufferer until he gets better. The cure might take a week, but it always works. My method is repeatable and perfectly reliable, and I've published my cure in a refereed scientific journal (there are now any number of phony refereed scientific journals). And, because (in this thought experiment) science can get along without defining theories, without falsifiability, I'm under no obligation to try to explain my cure, or consider alternative explanations for my breakthrough — I only have to describe it, just as lead in gasoline is being described as inversely correlated with crime rates in the linked article.

> Is this as strong as exposing a test population and comparing it to a control? No. But neither is it meaningless pseudo-science.

But that is exactly what it is -- meaningless pseudoscience -- on the ground that no one is crafting and then testing theories about the correlation. Until we know why A is correlated with B, until we can demonstrate a cause-effect relationship and make falsifiable predictions based on the theory, it's not science.

> But not everything worth investigating (and worth knowing) is amenable to that type of study.

Yes, I agree, science can't provide answers to questions not amenable to the scientific method (i.e. "that type of study"), and not all important questions have this property.


Well in the case of lead wouldn't the prediction be: a jurisdiction that removes lead from its petroleum products will experience a significant decrease in crime rates about 20 years later?


Not without a testable, falsifiable explanation. Observations (i.e. descriptions) can't be falsified, that's reserved for explanations. If I say, "the night sky is filled with little points of light", that's hardly falsifiable. But if I say, "those points of light are actually thermonuclear furnaces like our sun, but at greater distances", that claim is open to meaningful test and possible falsification.

Here's why a testable, falsifiable theory is required for science. Let's say I'm a doctor and I've created a revolutionary cure for the common cold. My cure is to shake a dried gourd over the cold sufferer until he gets better. The cure might take a week, but it always works. My method is repeatable and perfectly reliable, and I've published my cure in a refereed scientific journal (there are now any number of phony refereed scientific journals). And, because (in this thought experiment) science can get along without defining, falsifiable theories, I'm under no obligation to try to explain my cure, or consider alternative explanations for my breakthrough — I only have to describe it, just as the linked article describes the correlation between lead in gasoline and the crime rate.

Because I've cured the common cold, and because I've met all the requirements that social psychology recognizes for science, I deserve a Nobel Prize. Yes or no?


I welcome your strong defence of best quality science. The general public needs to know how the stronger sciences differ from the softer sciences.

However, this post is needlessly rude.


  The only way to get around these obstacles would be to 
  feed one group of people doses of lead and compare them to 
  another in a controlled setting, or isolate two groups of 
  people, give one group the right to birth control and 
  abortions, deny the other group those rights, and keep 
  them from finding out about each other. Things that cannot 
  be done for ethical reasons, and things that prevent 
  social psychology from rising to the level of science.
And yet in another comment, you say that cosmology, which has the same problem with not being able to vary the inputs and observe the effects on the outputs, is a real science. Why? Because it offers falsifiable hypotheses; you can make a prediction based on certain data, then test that prediction against other data.

The exact same is true of this topic. As I pointed out in my comment above, in portions that you conveniently ignored, there are strong predictions that this research makes, which can be tested. The original paper on this topic was written in 1999, and there is already 15 years worth of additional data since then; the next 10 to 15 years will provide even more data, which could falsify or could be consistent with this hypothesis.

  This is why social psychology cannot be a science, and it 
  explains why the field has the terrible reputation it has 
  and deserves.
I don't know why you bring up social psychology, as this study is not social psychology. It's more environmental sociology. Social psychology is the study of how people's behavior is related to their beliefs and attitudes about other people. This study is about how chronic, population wide lead poisoning relates to criminal behavior.

And while I share your skepticism about social psychology, the mere presence of corrupting influences such as the ones you mention, the desire for snappy, headline-ready results, does not mean that an entire field is devoid of value or not science. There are other fields, such as pharmacology, which likewise have troubling corrupting influences, and yet can also be real science that produce real value.

Anyhow, we've diverged pretty far from the original topic, as the original topic is not even within the field of social psychology.

  you haven't the slightest idea what makes science science.

  you have no idea what you're talking about. Not a clue

  you do not know what it is. How do I know this? You 
  defended social psychology for over four hundred words 
  without even mentioning it.
Please refrain from the ad-hominem attacks. They bring the level of the discussion down considerably.

I do not mention social psychology because this research is not social psychology.

This research is founded on well known, rigorous research on the effects of lead poisoning.[1] This is not some surprising, out-of-left-field result which came out of the blue from some small study on a handful of college undergrads, which is the problem with many psychological and social psychology findings; this is based on building on many years of research and meta-analysis of epidemiological research. The original paper on this topic[2] was written in 1999, follow up papers from other authors have been published in 2007[3].

There have been further studies confirming this effect; this 2008 paper in PLOS Medicine[4] measured prenatal blood lead levels in pregnant mothers, childhood lead levels, and later correlated that with arrest rates. They too found a strong correlation. Other studies on the same cohort have shown a strong correlation between blood lead levels and reduced brain mass[5].

Here's a paper that compares several of the hypotheses that you have brought up[6]. Now, I take this paper with a large grain of salt, because it clearly comes from a biased source, the Heartland Institute, which is clearly biased towards libertarian findings; and the point of the paper is to argue against drug prohibition, or excessive enforcement of it (I am sympathetic to that viewpoint, but view their research on the topic with a heavy dose of skepticism). However, they compared several of the proposed determinants of violent crime rates, such as incarceration rates, access to legal abortion, environmental lead, and so on, and the only one of them (outside of the one that they're obviously promoting, drug prohibition) which held up with a consistent correlation was environmental lead.

[1]: https://en.wikipedia.org/wiki/Lead_poisoning

[2]: http://www.ricknevin.com/uploads/Nevin_2000_Env_Res_Author_M...

[3]: http://www.nber.org/papers/w13097.pdf?new_window=1

[4]: http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fj...

[5]: http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fj...

[6]: http://news.heartland.org/sites/default/files/c11845.pdf


> The exact same is true of this topic.

No, this is false. Try to imagine a conclusive falsification of the claim that's being made in the linked article. Falsification doesn't mean casting doubt on a hypothesis, it means proving it wrong. In fields such as the one under discussion, with p-values typically in the range 0.01 to 0.05, nothing is ever falsified. Some ideas are abandoned through embarrassment, but none of them are ever falsified.

If I say all swans are white, someone can falsify my claim by locating a black swan. If i say that a reduction in the crime rate might have a cause-effect relationship with a reduction in the lead content of gasoline, that's a perfect article for social psychology, because it's not possible to argue against it in a scientific sense.

> Please refrain from the ad-hominem attacks.

My posts aren't being downvoted because of their tone, they're being downvoted because my position is correct and it makes people uncomfortable to hear that so much of modern science ... isn't science.

Apropos, here's Richard Feynman making the same points, for the same reason, 40 years ago: http://neurotheory.columbia.edu/~ken/cargo_cult.html

> the only one of them (outside of the one that they're obviously promoting, drug prohibition) which held up with a consistent correlation was environmental lead. [emphasis added]

I shouldn't have to say this, but correlation, however consistent, doesn't equal causation, and causation -- testable, falsifiable theories -- is the foundation on which science is built.

Ask yourself why Creationism isn't taught in public school science classrooms. This is so because Creationism isn't science. That, in turn, was established in a trial -- several, actually -- in which the court's decision was based on the fact that science was shown to require falsifiability, not mere argument. Here's one such court ruling:

http://en.wikipedia.org/wiki/McLean_v._Arkansas

Quote: "The judgment defined the essential characteristics of science as being:

   * It is guided by natural law;
   * It has to be explanatory by reference to natural law;
   * It is testable against the empirical world;
   * Its conclusions are tentative, i.e. are not necessarily the final word; and
   * It is falsifiable."
Think about this. If your position were accurate, the Creationists would have the right to present Creationism -- argument without falsifiability -- as science in public schools.


  No, this is false. Try to imagine a conclusive 
  falsification of the claim that's being made in the 
  linked article. Falsification doesn't mean casting doubt 
  on a hypothesis, it means proving it wrong. In fields 
  such as the one under discussion, with p-values typically 
  in the range 0.01 to 0.05, nothing is ever falsified. 
  Some ideas are abandoned through embarrassment, but none 
  of them are ever falsified.
Are you trying to say that the only work that can ever be falsified is that which is black and white, cut and dried, you will just be able to pull a counter example out an someone will go home in shame because their pet theory was disproven?

That's not how the majority of science works. The majority of science is statistical, and noisy, with lots of confounding variables. That doesn't mean that it's not falsifiable; just that it's messy, it doesn't follow some neat perfect model of how science is supposed to work.

This topic, whether environmental lead leads to increased crime, absolutely is falsifiable, just as falsifiable as the laws of thermodynamics, which are likewise statistical in nature. Now, the laws of thermodynamics are a lot easier to test, and you can get much bigger sample sizes much more easily; but that doesn't have any bearing on whether a theory is falsifiable, just how easy the process is.

Lack of falsifiability means that a theory makes no predictions. It means that there is no way to distinguish a world in which the theory is true, from one in which it is not.

  If i say that a reduction in the crime rate might have a 
  cause-effect relationship with a reduction in the lead 
  content of gasoline, that's a perfect article for social 
  psychology, because it's not possible to argue against it 
  in a scientific sense.
Of course it's possible. You would just need to show sufficient evidences of cases of long term, widespread (population wide for a large enough population) increases in environmental lead where the crime rate did not increase 20 years later, or likewise widespread decreases in environmental lead where it did not decrease 20 years later. If you managed to come up with enough data of that sort, without having selectively chosen the data solely for that purpose (or with some other biased methodology that caused you to prefer data that prefers one result over another), that would be a falsification.

Other possible falsifications would be to test blood lead levels on a controlled population, and then observe that population's tendency towards criminal activity. If environmental lead were strongly correlated, but blood lead levels were not, then that might indicate that the causation was not ingested lead, but some other variable that was predicting both, such as industrial activity or development levels.

  My posts aren't being downvoted because of their tone, 
  they're being downvoted because my position is correct and 
  it makes people uncomfortable to hear that so much of 
  modern science ... isn't science.
There is a lot of modern science that is flawed. On the other hand, there is a lot of science from any era that is flawed. Pseudo-science has existed as long, if not longer, than science. No one is afraid to admit this. I am well aware of poor science, junk science, and pseudo science, as are many people in this thread. You have provided a lot of arguments against junk science in general, but have not provided one bit of evidence that this study is junk science.

I don't downvote, I prefer to make my points explicitly in writing (unless it's just someone who is a blatant troll). You have been behaving poorly in this thread; trying to claim that I don't know what science is, rather than actually addressing my points. You have been criticizing the research by pointing out completely different fields which produce dubious results for sensation headlines (epidemiology and social psychology are quite different). You seem to be arguing from emotion, as you have some kind of prejudice, possibly well deserved, against certain fields of study; but you're now applying that against other, completely unrelated research, instead of actually engaging with the science to try to learn something about how the world works.

  I shouldn't have to say this, but correlation, however 
  consistent, doesn't equal causation, and causation -- 
  testable, falsifiable theories -- is the foundation on 
  which science is built.
Falsifiability does not imply that you have established causation. A correlation is just as falsifiable as a causal relationship; all you have to do is show sufficient evidence of the same two variables without the given correlation. Likewise, you can have completely unfalsifiable causal statements; like "God made the heavens and the earth."

You are drifting further and further from actually engaging the topic at hand; all you are doing is rambling about some of your pet peeves about bad science and pseudo-science, but you haven't established that the study in question has anything to do with them.

  Think about this. If your position were accurate, the 
  Creationists would have the right to present Creationism 
  -- argument without falsifiability -- as science in public 
  schools.
I have no idea how you are getting a lack of falsifiability from this study at all, and thus no idea how you're linking it to creationism. Creationism doesn't make predictions. This study does. Those predictions can be tested. Yes, they are statistical in nature, and subject to confounding factors and measurement error, but that's the nature of science. Feynman's example of the oil drop experiment was likewise subject to similar kinds of confounding factors and measurement errors; luckily, that was one that was a lot easier to collect data on so it could be much more easily refined.

Would you say that the relationship between smoking and cancer is bad science? The science there has all of the same issues; there are ethical issues with asking someone to smoke in order to determine causation, so all you can do is population wide observational studies and observe a lagged rate of cancer among a population that is strongly correlated with the smoking rate 20 years earlier, and the higher rate of cancer among those who smoke than those who don't. The combination of lagged effect, strong correlation, and explanatory science based on known mechanisms of acute toxicity can all combine to make a fairly compelling argument.




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