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

What would you measure differently if you were starting again?

emily_PDX 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…

I read this differently. The confidence in this thread is running ahead of the evidence, and I would rather the uncertainty were stated than smoothed over because it is unsatisfying.

emily_PDX 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…

emily_PDX has the substance of this right. The condition it depends on is worth stating. Yes, and the corollary is less popular: if the reasoning holds, it also holds where it produces an answer we do not like.

emily_PDX 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…

Thank you — that is the clearest version of this I have read, and I have read a lot of them. Taking it to my next appointment.

Clinical perspective, offered as context rather than as advice. 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.