Wilks’ test (1938) constitutes a major contribution to statistics and in practical applications. It is admittedly a classical method but even so it is of real interest because it is highly convenient to use. We hope to illustrate this in the following article by means of a study in the field of traffic psychology. In this demonstration, we start from a “characterization questionnaire” filled in by three populations of drivers and we test the population effect working from categorical data and 3-way tables. The differentiating power of the items is then examined and ranked in decreasing value. Through this example, we thus show the scope of Wilks’statistics and their highly general import with qualitative or category-specific data, compared with other techniques.