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.

dave_SLC said:

If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.

Agreed, and one caution: a single measurement is not a measurement. Anything that moves day to day needs a trend before it means anything at all.

dave_SLC said:

If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.

This answered a question I did not know how to ask. I will report back once I have actually tried it.

Adding the clinical framing, because it changes how the question reads. The mechanism and the magnitude are separate questions. Agreeing that something happens says nothing about whether it happens enough to act on.

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. Carry on.