Quantifying the accuracy of tells

[SplawnDarts]

I believe most people who have read Caro's book of tells will agree that the "accuracy" figures for the tells are essentially meaningless except for purposes of comparison.

I can think of at least one reason why this is true: they fail to take into account background probability. If it's 99% likely that your opponent is strong based on previous action, and you get a tell that, with 80% raw accuracy, tells you he's strong, have you learned much of anything? Not really.

The purpose of this thread is to create a new system for quantifying tells & using them in decisions. It should have these properties:
0) Mathematically sound
1) Useful for computation about what play to make (& ideally simple enough to use at the table)
2) Addresses the issue of background probability
3) Boils down to a number (or a few numbers) that could be listed for each tell in a book like Caro's.
4) Addresses the other issues raised on the first 2 pages of chapter 2 in Caro's book.

I have some ideas I'll state later.