A Method for Studying Differences between Groups

The researcher in behavioral or biological science has available a large arsenal of methods for studying the nature and statistical significance of differences between various groups of individuals. He may use any of a wide variety of univariate methods to test hypotheses about differences in location, in dispersion, in correlation between pairs of attributes, etc. In a multivariate situation methods are available to test hypotheses about mean vectors, variance-covariance matrices, correlation matrices, factor structures, etc. There are two points of view involved in studying the nature of differences between groups. One point of view is descriptive, and has traditionally been treated under the topic of estimation in statistics. The other usually involves a question as to whether it is reasonable to assume that some hypothesized model about the nature of differences between populations is in fact true, and has usually been treated under the ~pic of tests of hypotheses. The descriptive and inferential points of view must of necessity often overlap.