Okay, but let's stop and think about it for ten seconds: Of course drinking a slightly different brand of milk doesn't make you live 4.5 years longer; the headline claim is obvious nonsense. (And as I understand it, it's now thought that to the extent there is any difference, it's in favor of the high-fat milk.)
So then the conclusion seems to be that confounding factors have an extremely strong effect on the conclusion, even when the investigators have tried hard to screen them out.
Why? What went wrong with the attempts to screen out the confounding factors?
So then the conclusion seems to be that confounding factors have an extremely strong effect on the conclusion, even when the investigators have tried hard to screen them out.
Why? What went wrong with the attempts to screen out the confounding factors?