Beta Binomial ConjugacyPrior h(ฯ)โผBeta(ฮฑ,ฮฒ)h(\sigma) \sim \text{Beta}(\alpha, \beta)h(ฯ)โผBeta(ฮฑ,ฮฒ) Likelihood g(xโฃฮธ)โผBinomial(n,x,ฮธ)g(x|\theta) \sim \text{Binomial}(n, x, \theta)g(xโฃฮธ)โผBinomial(n,x,ฮธ) Posterior f(ฮธโฃx)=g(xโฃฮธ)h(ฮธ)โซฮธg(xโฃฮธ)h(ฮธ)dฮธf(\theta | x) = {{g(x | \theta) h(\theta)} \over {\int\limits_{\theta} g(x|\theta) h(\theta) d \theta}}f(ฮธโฃx)=ฮธโซโg(xโฃฮธ)h(ฮธ)dฮธg(xโฃฮธ)h(ฮธ)โ โดf(ฮธโฃx)โผBeta(ฮฑ+x,ย ฮฒ+nโx)\therefore f(\theta | x) \sim \text{Beta}(\alpha + x,~\beta + n - x)โดf(ฮธโฃx)โผBeta(ฮฑ+x,ย ฮฒ+nโx)