Jeffreys interval. Beta distributions are the
standard conjugate priors for binomial distributions
and it is quite common to use beta priors for inference
on p (see Berger, 1985).
Suppose X ∼ Binn p andsuppose p has a prior
distribution Betaa1 a2; then the posterior distribution
of p is BetaX + a1 n − X + a2. Thus a
1001 − α% equal-tailedBayesian interval is given
by