There is a fair share of ignorance of stats to go around, but in the biological sciences and in medicine, getting a big enough n is often practically difficult or impossible. Sometimes it's funding for the study that is to blame. But biology is messier than we often like to admit to ourselves. Sometimes it's just hard to get the materials. I was in a session just this week that showed a gene therapy cure for two kids who were cured of lysosomal storage disorder. It was incredible. But still an n of 4 I think. The process of growing the cells and transferring the genes is so time consuming and difficult, that's the best they could do. That's an extreme case to be sure, but even more mundane stuff can suffer. For example, if your study requires a muscle biopsy instead of a blood test, your n is going to be lower because muscle biopsies are a tough sell to patients. People, animals, and cells are all a lot more fickle than bits and electrons most of us around here are accustomed to working with.
