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.

I would rather be corrected than agreed with, if it comes to it.

One concrete data point for the thread. One practical note: write down what you did and when, before you need it. Reconstructing a timeline from memory three months later is how people end up unable to answer the one question that would have resolved it.

Following on from kate.chem — and this may be the naive question:

What would you measure differently if you were starting again?

lisa_labSD said:

One practical note: write down what you did and when, before you need it.

Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. The counter-case has not been addressed. Somebody upthread described the situation that does not fit, and the thread moved on rather than engaging with it, which is the failure mode this board is supposed to avoid.

Moderator note: leaving this open. It is being argued well and the disagreement is the useful part. Thread quality here is what the rules are for. Keep it up.