4.8. Concluding Remarks

It must be remembered that all the analyses presented in this chapter assume the equality of the variance-covariance matrices of the rows of matrix ε. If in a multiway classification, this assumption of the homogeneity of the variance-covariance matrix is not satisfied, the analysis presented here may not be appropriate. We therefore strongly recommend that some appropriate tests for the homogeneity of the variance-covariance matrices be applied to the data prior to performing any multivariate analysis of variance. The equality of variance-covariance matrices can be tested using the DISCRIM procedure. See SAS/STAT User's Guide, Version 6, Fourth Edition, Volume 1, for details.