I see. > suggesting biological relevance one might not expect with a statistical reversion to the mean. Just going to note here that regression to the mean is

I see. > suggesting biological relevance one might not expect with a statistical reversion to the mean. Just going to note here that regression to the mean is not 'just' statistical. It happens any time two variables are not perfectly correlated. The imperfect correlation could be due just as easily to 'biological relevance' as it could be to some sort of more purely statistical random error like rater error, so pointing out biology is no evidence. (As in the classic example of the flu patient going to the doctor and recovering afterwards; they really were biologically sick and really did biologically recover.)