Calculate Poisson probabilities

The Poisson test

compares a count of objects or

subjects (such as the number of

cars or people) in a specified

domain (for example a street

during a certain period) with

an expected number. The Poisson

test can be used as an

alternative to the Binomial

distribution in the case of

very large samples. Also, the

Poisson test can be used to

study how the chances of

observing none, one, two or

more 'accidents' or 'malfunctions'

in the domain are distributed.