has part has_specified_input has_specified_output achieves_planned_objective data transformation median calculation false positive rate Brown Forsythe test Orlaith Burke Alejandra Gonzalez-Beltran Philippe Rocca-Serra adapted from Wikipedia and Brown, M. B., and A. B. Forsythe. 1974a. The small sample behavior of some statistics which test the equality of several means. Technometrics, 16, 129-132. http://www.statmethods.net/stats/anovaAssumptions.html The hovPlot( ) function in the HH package provides a graphic test of homogeneity of variances based on Brown-Forsyth. In the following example, y is numeric and G is a grouping factor. Note that G must be of type factor. # Homogeneity of Variance Plot library(HH) hov(y~G, data=mydata) hovPlot(y~G,data=mydata) the Brown Forsythe test is a statistical test which evaluates if the variance of different groups are equal. It relies on computing the median rather than the mean, as used in the Levene's test for homoschedacity. This test maybe used to, for instance, ensure that the conditions of applications of ANOVA are met. homoskedasticity test equal variance testing objective p-value ready for release