pat_auckland said:

There is a difference between no evidence and evidence of no effect, and this subject is one where the two get swapped freely in both directions.

Second this. I had assumed I was the exception until I read this.

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.

Ask again with the specifics and you will get a better answer than this one.

carl_compliance 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…

Can confirm. Same sequence, different timescale. The detail I would add is minor and it is already implied above.

carl_compliance 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…

There is a second half to this that has not been said yet. Start from the measurement rather than the conclusion. Almost every disagreement here turns out to be two people measuring different things and comparing the numbers anyway.

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