A Note on Presenting What Predictive Validity Numbers Mean

Abstract

Descriptions of validity results based solely on correlation coefficients or percent of the variance accounted for are not merely difficult to interpret, they are likely to be misinterpreted. Predictors that apparently account for a small percent of the variance may actually be highly important from a practical perspective. This study combined two existing data sets to demonstrate alternative methods of showing the value of the Graduate Record Examination General Test (GRE) as an indicator of first-year graduate grades. The combined data sets contained 4,451 students in six graduate fields: biology, chemistry, education, English, experimental psychology, and clinical psychology. Students within a department were divided into quartiles based on GRE scores and on undergraduate grade point average (UGPA), and the percent of students in the top and bottom quartiles earning a 3.8 or higher GPA in their first year of graduate study was noted. Even after controlling for undergraduate GPA quartiles (i.e., looking at GRE quartile differences within GPA quartiles), substantial differences related to GRE quartile remained.