BethLabQueen said:

For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.

I read this differently from BethLabQueen, on substance rather than tone. I would resist the confidence. Half of what this board was certain about two years ago has since been quietly dropped, and nobody went back to correct the threads.

That is the short version; the long version is somebody else's post.

BethLabQueen said:

For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.

That is right, and it stops being right at the edges. The general case is well behaved; the interesting cases in this thread are all at the boundary where the general case breaks.

BethLabQueen said:

For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.

Thank you for spelling out the reasoning rather than just the conclusion. Taking it to my next appointment.

Clinical perspective, offered as context rather than as advice. The version of this that has an answer is narrower than the version being asked. Narrow it and it becomes tractable; leave it broad and the thread will produce nine confident and incompatible replies.

Closing the loop on my own question.

For the archive: it took about six weeks rather than the two I expected, and the difference between those two numbers was the whole of my problem.