"The bigger problem is that the suggested interpretation of the end result, with the fit line suggesting that a "normal" P/B right now would be 1.545 on that trend line, doesn't pass the sniff test given the 15 year average of 1.40. No, I'm sorry, it's utter nonsense and it's just plain wrong."

I respect your opinion, but I guess we'll have to disagree there. I do think that IV is closer to 1.54 than to 1.40 at present, based on the methodology I've described. However there's uncertainty in both of our estimates.

Apparently Buffett agrees with me, as he repurchased stock in Nov 2023 at 1.51x known book. Since Nov 2023 he has repurchased stock at higher P/B, too, as high as 1.60x known book, but those purchases were from long-time owners, and may have been slightly above his estimate of IV.