From the other side of the consultation, briefly. The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either. Those three things can all be true at once, and most arguments here are two people holding different parts of that.

traveltech_sara said:

The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either.

This matches mine closely enough to be worth saying so out loud. Nothing to add that would improve it.

traveltech_sara said:

The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either.

Coming at traveltech_sara’s question from a different direction. Worth answering the question that was asked rather than the one behind it. The narrow version usually has an answer; the broad version usually does not, and answering the broad one is how a thread stops being useful.

One concrete data point for the thread. Give anything pharmacological four weeks before you judge it, and give anything measured weekly a four-point rolling average before you call it a trend.

One thing that is still open after traveltech_sara’s answer:

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