I do understand what standard deviation is, and I do understand that it is possible that a 8.6 degrees difference would be significant. What I meant was that NOAA wouldn't be highlighting this unless it was.
Anyway, it's public data, and we can settle this pretty easily, right?
I other words, (again, if your calculations are correct) if this were a typical HN discussion about A/B testing a conversion goal, we'd all be ridiculing anybody who suggested a result almost 3 standard deviations from the mean _wasn't_ "statistically significant", yet climate change (sceptics|denialists) will no doubt _still_ argue the relevance of this…
The bigger problem (as others have alluded to) is that we don't really know what the tail of the distribution looks like. There's no obvious reason to think it's gaussian.
I do understand what standard deviation is, and I do understand that it is possible that a 8.6 degrees difference would be significant. What I meant was that NOAA wouldn't be highlighting this unless it was.
Anyway, it's public data, and we can settle this pretty easily, right?
http://www.ncdc.noaa.gov/temp-and-precip/time-series/index.p... has the raw data in CSV form going back to 1895.
The standard deviation is 2.89 (assuming my calculations are correct)