Bartlett correction
= Bartlett correction
{c}
A Bartlett correction rescales a regular <likelihood-ratio test statistic> so that its null expected value matches its limiting chi-squared degrees of freedom to a higher asymptotic order. If $\mathbb E_0W=d(1+b/n+O(n^{-2}))$, divide $W$ by $1+b/n$. The operation uses a model-specific <Bartlett correction coefficient>; matching the mean alone is not a general proof of any claimed distributional error rate.