Poisson Distribution

Poisson distribution is a discrete probability distribution that describes the probability of a given number of events occurring in a fixed time interval. Instead of time intervals, units of length, space, etc., can be used, too. Poisson distribution describes the behavior of the so called rare events that have a small probability of occurrence, and thus even in a large amount of observation their appearance is infrequent. Poisson distribution is often used in the analysis of stochastic processes, especially in the so called Poisson process. Phenomena that are well-modelled by this process are, e.g. requests for telephone calls at a switchboard or particle emissions due to radioactive decay.
The program enables to work with the Poisson probability distribution. For given parameter lambda (average rate of the event occurrence), the probability mass function, mean, variance, modus and median of the distribution are computed. The graphs of probability mass function and distribution function are shown. The user can also evaluate probability that the random variable lies in the given range.