The Pearson law is parameterized by
(no unit). Another name
for the Pearson law is Chisquared law. If random variables follows the Normal law with mean 0 and variance 1, then: 

Let's take a random variable following the Pearson law, then:  
is distributed according to the following density of probability, where: 

And where is a Gamma function. 

With mean: 

With variance: 

With standard deviation: 
