Poisson Distribution

A Poisson distribution is a discrete distribution that shows the probability of how often a particular event will occur in a certain interval of time or space. The event being measured must occur at a known average rate, and it shouldn't matter how long it's been since the last event. For example, one could use a Poisson distribution to determine how many red cars usually stop at a particular intersection from the time a traffic light turns yellow up until it turns green again. It could be zero, or twelve, or any other number, but there will typically be a mean somewhere between two extremes, as shown in the example graph above. This distribution was first used in 1837 by Siméon Denis Poisson, a French mathematician and physicist.

--Emma Stanislawski