A narrower follow-up, since the general answer is now clear:

What would you measure differently if you were starting again?

Reporting back.

Reporting back with a partial result, because a partial result is still better than silence. Two of the three things suggested helped; I cannot separate them and I am not going to pretend otherwise.

DanielChem_CHI said:

Say what you would expect to see if you were wrong, before you look.

Fair, and it stops being fair at the extremes. The middle of the range is well understood; the ends are where the honest answer is that nobody knows.

DanielChem_CHI said:

Say what you would expect to see if you were wrong, before you look.

This is exactly what I could not find anywhere else. Printing the relevant bit and taking it with me.

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.