pete_nash said:

That is right, and it stops being right at the edges.

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

pete_nash said:

That is right, and it stops being right at the edges.

There is a second half to this that has not been said yet. 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.

If somebody has the primary source to hand I would rather cite it than paraphrase it.

Adding the numbers, since they settle part of this. Practical: whatever you change, write down the date and the reason. In three months the reason is what you will have forgotten, and the reason is what makes the record worth having.

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

Did your prescriber agree with that reading, and if not what was their objection?

PharmacoVig_BOS said:

Practical: whatever you change, write down the date and the reason.

This is where I part company with the consensus forming above. The objection nobody has made: this only works if the measurement is doing what we assume it is doing, and that assumption has not been tested here.