How do scientists determine the probability of rare events occurring?
Rare events are, well, very rare, and this can make it difficult to know how likely they are to occur in any given time frame. Statisticians must look at a large enough body of data to make any useful prediction about it. But how do you find a large enough sample of events that dont happen very often? Fortunately, mathematicians have a useful tool to do this: the Poisson distribution, also known as the “law of large numbers.” The Poisson distribution describes the probability that a random, rare event will occur in a given interval of time, such as the number of no-hitters occurring over and entire 162-game baseball season. While the probability of the event occurring is very small, the number of opportunities for it to happen is so large that the event actually occurs a few times. The longer the time interval, the more the data begins provide a pattern from which predictions can be made. The Poisson distribution is particularly useful in the study of how diseases spread through popula
