VARIANCE AS A FACTOR EFFECT IN INTERDISCIPLINARY STUDIES OF AGRICULTURAL SYSTEMS

Studies of interrelationships among factors typically focus on factor effects related to the mean response. In some instances, response variances, as well as, or even rather than, response means, may be affected by the factors under consideration. In this paper, generalizations of Levene\u27s test and the Jackknife test to two-factor experimental designs are studied via simulation studies to assess their ability to identify differences in the variance as an interaction effect or as a factor main effect. These tests are then applied to a particular example where relationships between chile plants and two prominent pests of chile plants -nematodes and yellow nutsedge -- are under study. This example illustrates the utility of these tests in studying relationships among factors in agricultural systems