A narrower follow-up, since the general answer is now clear:
How would you tell the difference between that and the alternative explanation?
PharmacoVig_BOS said:One practical note: write down what you did and when, before you need it.
I read this differently. The confidence in this thread is running ahead of the evidence, and I would rather the uncertainty were stated than smoothed over because it is unsatisfying.
PharmacoVig_BOS said:One practical note: write down what you did and when, before you need it.
That is right, and it stops being right at the edges. The general case is well behaved; the interesting cases in this thread are all at the boundary where the general case breaks.
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Shop Reference StandardsPharmacoVig_BOS said:One practical note: write down what you did and when, before you need it.
This answered a question I did not know how to ask. I will report back once I have actually tried it.
OP back with an update, since a thread like this is useless without one.
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.