<P> An F - test is any statistical test in which the test statistic has an F - distribution under the null hypothesis . It is most often used when comparing statistical models that have been fitted to a data set, in order to identify the model that best fits the population from which the data were sampled . Exact "F - tests" mainly arise when the models have been fitted to the data using least squares . The name was coined by George W. Snedecor, in honour of Sir Ronald A. Fisher . Fisher initially developed the statistic as the variance ratio in the 1920s . </P> <P> Common examples of the use of F - tests include the study of the following cases: </P>

When do we use f test in statistics