Dr.NutriCornell said:There is a difference between no evidence and evidence of no effect, and this subject is one where the two get swapped freely in both directions.
There is a second half to this that has not been said yet. Order of operations matters more than any single choice here: establish a baseline, change one thing, wait long enough for it to express itself, then measure again under the same conditions.
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.
One thing that is still open after Dr.NutriCornell’s answer:
How would you tell the difference between that and the alternative explanation?
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Shop Reference Standardsraj_cambridge said:If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.
Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. Not convinced. The evidence being cited is consistent with the conclusion and also consistent with two other conclusions nobody has ruled out.
raj_cambridge said:If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.
Correct as far as it goes. The part it does not cover is what to do when the honest answer is "not enough data", which is more often than anyone likes.