Adding the clinical framing, because it changes how the question reads. The mechanism and the magnitude are separate questions. Agreeing that something happens says nothing about whether it happens enough to act on.

labquiet_amy said:

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

There is a second half to this that has not been said yet. It helps to say which part of this you are uncertain about. A precise question gets a precise answer; a general one gets everybody’s favourite anecdote.

The figures, for anyone assembling their own picture. 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 long did you give it before you decided it was working?

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. No action needed from anybody.