 This ratio is not much used currently having been largely replaced by the use of the chi-squared test in testing for the homogeneity of samples.This measure compares the between-set variance of the sample proportions (evaluated for each set) with what the variance should be if there were no difference between in the true proportions of success across the different sets.Thus the measure is used to evaluate how data compares to a fixed-probability-of-success Bernoulli distribution.