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Etymology: Sir Ronald Aylmer Fisher, British statistician, 1890-1962
1 the variance between the means of several groups relative to the variance within the groups, used in the F-test in the analysis of variance.
2 the variance between or within treatments.
n a value used in determining whether the difference between two variables is statistically significant or stable. A larger variance is divided by a smaller variance, both of which are the results of analysis of variance procedures. The value for F is looked up in a table that shows the probability of occurrence of a ratio of this size.