Key Points Sigma represents the population standard deviation for a data set Sigma is used to measure process capability in ...

The reason we go through such a complicated process to define standard deviation is because this measure appears as a parameter in a number of statistical and probabilistic formulas, most notably ...

Fact checked by Suzanne Kvilhaug Reviewed by Chip Stapleton For a given data set, standard deviation measures how spread out the numbers are from an average value. This measurement of average variance ...

How to calculate standard deviation using the defining formula is explained. Discuss with students the need to go beyond averages to give a picture of what a sample is like. Consider real life ...