Variability within a set of scores is often expressed asstandard deviation. Another way to expressvariability is as variance, the square of the standard deviation. Analysis ofvariance (ANOVA) is one method of assessing the significance of the differencebetween means (hypothesis testing isanother method).

ANOVA is particularly useful when comparing more that two means. In at-test, for example, you would have toconduct separate tests to compare each mean against every other mean. ANOVAcompares all means simultaneously.