Dr.SurgeonPGH said:

It helps to ask what evidence would change your mind before you look at any.

Coming at Dr.SurgeonPGH’s question from a different direction. Take it one variable at a time. Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent argument can untangle them after the fact.

The figures, for anyone assembling their own picture. One practical note: write down what you did and when, before you need it. Reconstructing a timeline from memory three months later is how people end up unable to answer the one question that would have resolved it.

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

What would you measure differently if you were starting again?

HPLC_Greg said:

One practical note: write down what you did and when, before you need it.

I read this differently from HPLC_Greg, on substance rather than tone. Not convinced. The evidence being cited is consistent with the conclusion and also consistent with two other conclusions nobody has ruled out.

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.