Probability Distributions

A probability distribution tells you how likely different possible outcomes are for a random event or experiment. It maps out the chances of different results happening. It’s a way of saying, “Here’s everything that could happen, and how often I expect each one to happen.”

The commonly used probability distributions are normal (bell curve), binomial, Poisson, and uniform distributions.

Common pitfall: Different types of distributions need different types of analysis. Using the wrong type of distribution for analysis can lead to wrong results. Another common problem is assuming that data follow a normal distribution without testing for normality.