Dr.SurgeonPGH said:

The distinction that resolves most of these threads is between what is true on average and what is true for one person.

That holds where the measurement is reliable. Where it is noisy — and a lot of what gets tracked here is noisy — the same reasoning produces confident nonsense.

TomTeleRx said:

Agreed, with a caveat about community reputation: it is a lagging indicator.

Thank you for spelling out the reasoning rather than just the conclusion. I will report back once I have actually tried it.

Dr.SurgeonPGH said:

The distinction that resolves most of these threads is between what is true on average and what is true for one person.

This is where I part company with the consensus forming above. Not convinced. The evidence being cited is consistent with the conclusion and also consistent with two other conclusions nobody has ruled out.

Adding the numbers, since they settle part of this. Practical: whatever you change, write down the date and the reason. In three months the reason is what you will have forgotten, and the reason is what makes the record worth having.

Moderator note: the sourcing question belongs in the vendor section and has been split out.