Bartlett's test for variances: A test for equality of the variances of the number (k)of the populations. The test statistic can be given as follows
where s square is an estimate of the variance of population i based on vi degrees of freedom, and v and s square are given by
and Under the assumption that the populations all have the same B has a chi-squared distribution, variance with the k - 1 degrees of freedom. Sometimes used earlier for applying analysis of variance techniques or methods to assess the assumption of the homogeneity of the variance. Of limited practical value cause of its well known sensitivity to non-normality, so that the signi?cant result might be due to the departures from normality rather than to the different variances.