Negative Binomial Distribution Variance Calculator

For a negative binomial distribution (the number of failures $X$ before the $r$th success) with failure probability $p$ (and success probability $1-p$), the variance is given by: $${\sigma }^2=\frac{rp}{(1-p{)}^2}.$$

* Enter the number of successes $r$ (integer $\ge 1$) and the failure probability $p$ (with $0<p<1$).