EndoResFellow said:

Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the…

Mine went the same way, slower. Posting only so the count is not one.

Clinical perspective, offered as context rather than as advice. Worth answering the question that was asked rather than the one behind it. The narrow version usually has an answer; the broad version usually does not, and answering the broad one is how a thread stops being useful.

anna.melb_AU said:

Worth answering the question that was asked rather than the one behind it.

This matches mine closely enough to be worth saying so out loud. Nothing to add that would improve it.

anna.melb_AU said:

Worth answering the question that was asked rather than the one behind it.

Adding the part of the answer the thread has not reached. The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either. Those three things can all be true at once, and most arguments here are two people holding different parts of that.

Ask again with the specifics and you will get a better answer than this one.

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. Thread quality here is what the rules are for. Keep it up.