Displaced Poisson distribution
In statistics, the displaced Poisson, also known as the hyper-Poisson distribution, is a generalization of the Poisson distribution. The probability mass function is
where and r is a new parameter; the Poisson distribution is recovered at r = 0. Here
is the incomplete gamma function and s is the integral part of r. The motivation given by Staff is that the ratio of successive probabilities in the Poisson distribution (that is
) is given by
for
and the displaced Poisson generalizes this ratio to
.