One thing that is still open after SarahChen_PharmD’s answer:

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

TirzTom said:

The boring version of this is the one that works, and the boring version is: measure a baseline, change one variable, wait, measure again under the…

Careful with the causal language. Two things moving together in a period when five things changed is not a mechanism, and stating it as one makes the thread less useful to somebody reading it later.

TirzTom said:

The boring version of this is the one that works, and the boring version is: measure a baseline, change one variable, wait, measure again under the…

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.

Happy to go further on any of that.

TirzTom said:

The boring version of this is the one that works, and the boring version is: measure a baseline, change one variable, wait, measure again under the…

Thank you — that is the clearest version of this I have read, and I have read a lot of them.

Adding the clinical framing, because it changes how the question reads. The useful move here is to separate what is established from what is widely repeated. Those two sets overlap less than the confident tone of most write-ups suggests, and the second set is where nearly all the disagreement on this board comes from.