Beta and Bernoulli: Updating with Pseudo-Counts

A coin lands heads with an unknown probability p. Our belief about p is a beta distribution: a density on the interval from zero to one, here the front curve.

Its two parameters, alpha and beta, act like counts of heads and tails we have already seen. Their mean is alpha over alpha plus beta, and the more pseudo counts, the narrower the curve.

The rest of the narration is in the book's Companion.