Factors Influencing the Predictability of College Grades

A distribution of several hundred multiple correlation coefficients (R's) obtained at colleges and universities throughout the country among ACT scores and high school grades on the one hand, and firstyear college grades on the other, ranges from .29 through .80. Why is there such variability? Since the ACT tests are the same and presumably the high school grades measure roughly the same variables in all instances, the answer must depend on differences from campus to campus in one or more of the following factors: (a) the criterion is different, (b) the sample is different, or (c) the R's themselves unreliably represent the true association between predictors and criteria, because of careless reporting, atypical student samples, the use of very small samples, or other unusual circumstances. This report examines possible explanations of the fact that grades at some institutions are more predictable than those at others.