Postdiction Study of the Graduate Record Examination and Eight Semesters of College Grades1

Data from a postdictive study of the tests of the Graduate Record Examination and the eight semesters of undergraduate grade averages, each semester's average being computed independently of the rest, are presented. Postdictive validities of the aptitude portions of the GRE are essentially similar to predictive validities obtained earlier by the senior author. Both predictive and postdictive validity gradients over the eight semesters are relatively steep, with freshman grades having the highest correlations with the tests. The validity gradient for all advanced tests combined does not follow the pattern for the aptitude tests, but neither does it show the opposite gradient. Advanced test results are most highly correlated with sophomore grades, but the validity gradient over the eight semesters is relatively flat. A small scale extension of this research into post baccalaureate training indicated that senior grades were most predictive of graduate criteria, but a larger scale study is clearly called for. Possible implications for ability theory and for selection of graduate students are discussed.