hyun_seoul said:

The distinction that resolves most of these threads is between what is true on average and what is true for one person.

Coming at hyun_seoul’s question from a different direction. Say what you would expect to see if you were wrong, before you look. It is a small discipline and it changes what you notice.

Reprising the part of this that the last few posts have moved away from:

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 correction. That is slower than asserting, and it is the only version that survives being wrong.

Following on from hyun_seoul — and this may be the naive question:

What did you change at the same time, and can you separate the two now?

This was answered several pages up and is worth repeating rather than re-litigating:

If two explanations both fit, the useful question is which one predicts something the other does not. That is answerable; arguing about which sounds more plausible is not.

raj_cambridge 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…

Correct as far as it goes. The part it does not cover is what to do when the honest answer is "not enough data", which is more often than anyone likes.