Following on from LindaRN_retired — and this may be the naive question:
How would you tell the difference between that and the alternative explanation?
Closing the loop on my own question.
Update, and it is the boring outcome: nothing was wrong. The measurement I was reading had moved less than its own week-to-week variation, which somebody said upthread and I did not believe.
hank_denver said:If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.
Correct, and worth adding that it is reversible. Nothing being described here is a one-way door, which changes how cautious it is reasonable to be.
If somebody has the primary source to hand I would rather cite it than paraphrase it.
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Shop Reference Standardshank_denver said:If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.
That reframing is the part I needed. Sending this to two other people who asked me the same thing last week.
Adding the clinical framing, because it changes how the question reads. It is worth asking what the claim would look like if it were false. If nothing would look different, it is not a claim about the world and no amount of discussion will settle it.