Discriminant Function Analysis - Effect Size

Effect Size

Some suggest the use of eigenvalues as effect size measures, however, this is generally not supported. Instead, the canonical correlation is the preferred measure of effect size. It is similar to the eigenvalue, but is the square root of the ratio of SS_between and SS_total. It is the correlation between groups and the function. Another popular measure of effect size is the percent of variance for each function. This is calculated by: (λ_x/Σλ_i) X 100 where λ_x is the eigenvalue for the function and Σλ_i is the sum of all eigenvalues. This tells us how strong the prediction is for that particular function compared to the others. Percent correctly classified can also be analyzed as an effect size. The kappa value can describe this while correcting for chance agreement.