Integrated tail distribution (source code)

= Integrated tail distribution
{title2=$f_I(x)=\mathbb P(X>x)/\mathbb EX$}

For a positive random variable $X$ with finite nonzero <expected value> $\mu$, its integrated tail law has density $f_I(x)=\mathbb P(X>x)/\mu$ on $x\geq0$. The <tail integral formula for moments> normalizes it. For $r>0$ its exponential transform is $\int e^{rx}f_I(x)\,dx=[M_X(r)-1]/(\mu r)$, with extended-value interpretation when needed.