Adding the clinical framing, because it changes how the question reads. 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.
One concrete data point for the thread. Say what you would expect to see if you were wrong, before you look. It is a small discipline and it changes what you notice.
One thing that is still open after dave_SLC’s answer:
How would you tell the difference between that and the alternative explanation?
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Shop Reference StandardsPeptideChemSF said:Say what you would expect to see if you were wrong, before you look.
I do not accept the framing. The question has been narrowed to the version that has a tidy answer, and the part that was dropped is the part the OP actually asked about.