[dsacco]

> Most recent studies in psychiatry and social sciences that I have read, even those published in Nature, use sample sizes of around 50 people, which should be considered insufficient.

I disagree with your reasoning even if your conclusion is correct about the validity of those studies. Small sample sizes are not intrinsically bad and there’s no magic number to make sample sizes valid. It’s a sliding scale with statistical significance - with a large enough p value a relatively small sample size doesn’t mean the observed phenomenon isn’t there. In that case I would be more concerned about p value hacking or the researchers “presuming the conclusion from the outset” than the sample size.