Adding the clinical framing, because it changes how the question reads. If two explanations both fit, the useful question is which one predicts something the other does not. That is answerable; arguing about which sounds more plausible is not.
Adding the numbers, since they settle part of this. 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.
A narrower follow-up, since the general answer is now clear:
How would you tell the difference between that and the alternative explanation?
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Shop Reference StandardsTirzTom 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.