GraceAZ_72 said:

I changed one thing, left everything else alone, and waited the full interval before looking.

Same pattern here, and in the same order. I had assumed I was the exception until I read this.

GraceAZ_72 said:

I changed one thing, left everything else alone, and waited the full interval before looking.

There is a second half to this that has not been said yet. The useful move here is to separate what is established from what is widely repeated. Those two sets overlap less than the confident tone of most write-ups suggests, and the second set is where nearly all the disagreement on this board comes from.

One concrete data point for the thread. If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way. Most of the apparent contradictions in these threads dissolve at that step.

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

How would you tell the difference between that and the alternative explanation?

dan_philly said:

If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.

I read this differently from dan_philly, on substance rather than tone. I think the framing smuggles in the conclusion. Ask it the other way round and the obvious answer reverses, which usually means the question is doing the work.