Sample selection in genetic studies: impact of restricted range
I'll shortly be posting a preprint about methodological quality of studies in the field of neurogenetics. It's something I've been working on with a group of colleagues for a while, and we are aiming to make recommendations to improve the field. I won't go into details here, as you will be able to read the preprint fairly soon. Instead, what I want to do here is to expand on a small point that cropped up as I looked at this literature, and which I think is underappreciated. It's to do with sampling. There's a particular problem that I started to think about a while back when I heard someone give a talk about a candidate gene study. I can't remember who it was or even what the candidate gene was, but basically they took a bunch of students, genotyped them, and then looked for associations between their genotypes and measures of memory. They were excited because they found some significant results. But I was, as usual, sitting there thinking convoluted though...