Methods and formulas for the statistics in Tolerance Intervals (Nonnormal Distribution)

A commonly used measure of the center of a batch of numbers. The mean is also called the average. It is the sum of all observations divided by the number of (nonmissing) observations.

Formula

Notation

The sample standard deviation provides a measure of the spread of your data. It is equal to the square root of the sample variance.

Formula

If the column contains x ₁, x ₂,..., x _N, with mean , then the standard deviation of the sample is:

Notation

Term	Description
x i	i th observation
	mean of the observations
N	number of nonmissing observations