what is the parameter of the poisson distribution
In probability theory and statistics, the Poisson distribution (French pronunciation (pwaˈsɔ̃); in English often rendered / ˈpwɑːsɒn /), named after French mathematician Siméon Denis Poisson, is a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time or space if these events occur with a known constant rate and independently of the time since the last event. The Poisson distribution can also be used for the number of events in other specified intervals such as distance, area or volume.