Dr.NateNeph said:

Say what you would expect to see if you were wrong, before you look.

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.

Dr.NateNeph said:

Say what you would expect to see if you were wrong, before you look.

Genuinely useful, thank you. I had the facts and not the framework. Printing the relevant bit and taking it with me.

Adding the clinical framing, because it changes how the question reads. Order of operations matters more than any single choice here: establish a baseline, change one thing, wait long enough for it to express itself, then measure again under the same conditions.

newstart_MO said:

Order of operations matters more than any single choice here: establish a baseline, change one thing, wait long enough for it to express itself, then…

This matches mine closely enough to be worth saying so out loud. The detail I would add is minor and it is already implied above.

newstart_MO said:

Order of operations matters more than any single choice here: establish a baseline, change one thing, wait long enough for it to express itself, then…

Adding the part of the answer the thread has not reached. 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.