Tolerance interval

A tolerance interval, also known as a tolerance limit, is a statistical interval within which, with some confidence, a specified proportion of a population falls. This differs from a confidence interval in that the confidence interval bounds a population parameter (the mean, for example) with some confidence, while a tolerance interval bounds percentile range that represents a specified proportion of the population. In simpler terms, the confidence interval characterizes the behavior of the average while the tolerance interval characterizes the behavior of a range of individuals.

If the confidence is 100%, because the population distribution parameters are known exactly, then the tolerance interval reduces to a probability interval.