One thing that is still open after Dr.PathRoch’s answer:

What would you measure differently if you were starting again?

PharmacoVig_BOS 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…

I read this differently from PharmacoVig_BOS, on substance rather than tone. Filing an objection on the n=1 problem. Personal experience is genuine evidence about one person and very weak evidence about anybody else, and this thread keeps promoting the first into the second.

PharmacoVig_BOS 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.

PharmacoVig_BOS 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…

Genuinely useful, thank you. I had the facts and not the framework. Adding it to my notes with a link back to this thread.

From the other side of the consultation, briefly. 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.