The Poisson Distribution  
Summary 
the poisson distribution describes the distribution of events which occur randomly in a continuous interval. e.g. time, length, volume etc. the following conditions must apply:
the poisson distribution has only one parameter and that is λ the average number of occurrences of an event in a given time interval. i.e. a rate. the mean and the variance of the poisson distribution are both λ 
Key Skills 

Vocabulary 
poisson distribution, lambda, independent events, mean, variance, standard deviation, expected value. 