Constant-risk binomial proportion estimator
= Constant-risk binomial proportion estimator
{title2=$\delta(X)=\frac{X+\sqrt n/2}{n+\sqrt n}$}
For $X\sim\operatorname{Bin}(n,\theta)$, the <posterior mean> under $\operatorname{Beta}(\sqrt n/2,\sqrt n/2)$ has constant squared-error risk $1/[4(\sqrt n+1)^2]$. Its unique Bayes property and constant risk make it the unique <minimax estimator>.