 For example, the above parameterization differs from the parameterization in the linked article in the Poisson case.The two parameterizations are related by formula_11, where λ is the mean parameter, and so that the density may be written as
for formula_13, so 

This alternative parameterization can greatly simplify calculations in mathematical statistics.For example, in Bayesian inference, a posterior probability distribution is calculated as the product of two distributions.