It’s the nature of the study that parent comment is referring to. If a study is self-reporting, it’s an observational study which can only establish correlatio

It’s the nature of the study that parent comment is referring to. If a study is self-reporting, it’s an observational study which can only establish correlation, meaning the study can only say, “there might be something here that warrants a further research”. A clinical trial is needed to establish causation. So while 10k sample size reduces the error bars, it only increases the confidence that there might be something here worth doing a more rigorous study later.