Wilks's criterion: A measure for comparing the value of general purpose soil classifications

Summary Wilks's Criterion, the ratio of the determinants of the within-class and total dispersion matrices, is described. It can measure the relative goodness of a general purpose soil classification, and can be used to determine how many clusters are present in a population, and hence how many classes can reasonably be recognized. Its use is illustrated with two examples. In the first, three soil maps of the same area, but at different scales, are compared. In the second, classifications of a set of profiles are shown to have recognized only three clusters.