Normal linear-model confidence ellipsoid (source code)

= Normal linear-model confidence ellipsoid

With $\widehat\sigma^2=\|Y-X\widehat\beta\|^2/(n-p)$, a simultaneous $(1-\alpha)$ confidence region for $\beta$ is
$$
(\beta-\widehat\beta)^TX^TX(\beta-\widehat\beta)
\leq p\widehat\sigma^2F_{p,n-p}(1-\alpha).
$$