What is the difference between binomial distribution and poisson distribution?
Both the distributions are Discrete probability distributions. But the Binomial distribution is used to express the probability of one set of dichotomous alternatives i.e., success or failure on certain assumptions. The calculation of Binomial probability becomes tedious when n is large and / p is very small. When n is not known or infinity Binomial model cannot be applied. When the probability of occurrence of an event is very small ( p<0.1) and / n is very large (n>20) Poisson distribution is more appropriate for determining the required probabilities.Poisson distribution is used to describe the behaviour of rare and casual events. In fact Poisson distribution is a limiting case of Binomial distribution in case n is very large or not known or infinity.
