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.

jason_paloalto said:

Keep the original post as written when you update it, and add the correction underneath.

Coming at jason_paloalto’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.

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.

Following on from jason_paloalto — and this may be the naive question:

What did you change at the same time, and can you separate the two now?

Moderator note: a post naming a supplier has been edited. Discuss suppliers in the review sections, not here. Report rather than reply if it drifts again.