TrialNerd_Beth 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…

There is a second half to this that has not been said yet. The distinction that resolves most of these threads is between what is true on average and what is true for one person. Both are real; they answer different questions and get quoted as if they were the same one.

The figures, for anyone assembling their own picture. Keep the original post as written when you update it, and add the correction underneath. An edited-away mistake is invisible to the next person who makes it.

A narrower follow-up, since the general answer is now clear:

How would you tell the difference between that and the alternative explanation?

Dr.NateNeph said:

Keep the original post as written when you update it, and add the correction underneath.

Worth saying that the confident version of this is more useful to the person writing it than to the person reading it.

Dr.NateNeph said:

Keep the original post as written when you update it, and add the correction underneath.

That is right, and it stops being right at the edges. The general case is well behaved; the interesting cases in this thread are all at the boundary where the general case breaks.