Dr.ObesityLA said:

If two explanations both fit, the useful question is which one predicts something the other does not.

Adding the part of the answer the thread has not reached. It helps to ask what evidence would change your mind before you look at any. If nothing would, the discussion is not about evidence, and it is better to say so early than to spend nine posts discovering it.

The figures, for anyone assembling their own picture. The boring version of this is the one that works, and the boring version is: measure a baseline, change one variable, wait, measure again under the same conditions. Nobody wants that answer and it is still the answer.

Following on from Dr.ObesityLA — and this may be the naive question:

What would you measure differently if you were starting again?

anders_CPH said:

The boring version of this is the one that works, and the boring version is: measure a baseline, change one variable, wait, measure again under the…

I am going to disagree with the direction of travel here. The thread has converged on the tidiest answer rather than the best-supported one, and those are not the same thing.

Reporting back.

Reporting back for the archive rather than for the thread: I did the narrow version of what was suggested, gave it the full interval, and it settled. Posting it because threads without a follow-up are half a thread.