pete_nash said:

Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent…

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.

zoe_NC said:

Right, and one flattering data point from a group buy is not consistency.

This answered a question I did not know how to ask. Adding it to my notes with a link back to this thread.

pete_nash said:

Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent…

Pushing back on pete_nash here. I think the framing smuggles in the conclusion. Ask it the other way round and the obvious answer reverses, which usually means the question is doing the work.

Adding the numbers, since they settle part of this. One habit that pays for itself: post the method alongside the number. A figure without its method cannot be checked, and an unchecked figure is how this community accumulates folklore.

Moderator note: a couple of off-topic posts removed.