The ACT as a Predictor of College Success

ACT Validity Claims

ACT describes its test as one of several useful measures of a student's readiness for college and career, and the organization has produced research to support that claim. A 2012 ACT paper, for example, reported that composite scores helped predict students' longer-term success at both four- and two-year institutions, pointing to higher college GPAs and graduation rates among higher scorers. A 2016 ACT paper took aim at test-optional policies, arguing that scores still convey useful information even among applicants with identical high school GPAs: in ACT's telling, test results separate students who otherwise look alike on paper, so a school that disregards scores would wrongly treat every applicant with the same GPA as an equally strong bet. Critics counter that research produced by the test-maker itself starts from a predetermined position and cannot be treated as a neutral verdict.

Independent Studies of Correlations between ACT Scores and College Grades

Some independent researchers have a positive view of the predictive value of ACT scores. A 2010 paper authored at Princeton University considered the association of a number of variables, including ACT scores, with college GPA. According to the researchers, "it is clear that standardized admission test scores are statistically significant and substantively important predictors of college grades." Other researchers have come to different conclusions. A 2014 study of 33 test-optional universities found that students who chose not to submit standardized test scores had roughly the same average cumulative college GPA (2.83) as those who did submit test scores (2.88). The study included approximately 123,000 student records over eight academic years.

Independent Research on ACT Scores and College Graduation Rates

The connection between ACT scores and college graduation rates has also been explored by researchers. The authors of the 2010 Princeton paper cited above found no obvious links: "Admission test scores were not associated with the likelihood of graduating." The 2014 research on test-optional universities found almost no difference between the rates at which test score submitters and non-submitters graduated (less than 1%). A 2017 master's thesis written at Utah State University, on the other hand, found that ACT scores, specifically those for the English and Math sections, were "significant predictors" of graduation rates. That finding lines up, at least in part, with ACT's own claims about the predictive value of its scores.

Correlations between ACT Scores and High School GPA

In a master's thesis written by a graduate student at Marietta College in 2006, the high school GPAs and ACT scores of undergraduate applicants from both public and private high schools were analyzed. Correlations between high school GPA and ACT scores were found for both groups, although the link was much stronger for public than for private school students (correlation coefficient of .542 versus .334). Public school students included in the study had an average high school GPA of 3.40 and a mean ACT composite score of 22, while for private school students, the averages were 3.24 and 23 respectively. This research roughly aligns with a study conducted by ACT in 2016, which showed an average high school GPA of 3.40 and an average ACT score of about 23 among approximately 187,000 students tested.

Validity Comparisons between the ACT, the SAT, and High School GPA

A Yale University professor examined the issue of how well ACT scores predicted SAT scores and vice versa in 2005. This researcher found a correlation coefficient of .77, indicating a high degree of predictive validity (student scores on one of these tests tended to be similar to scores on the other). A number of researchers have concluded that high school grades forecast college GPA more reliably than either test does. The 2014 study of test-optional schools noted above, for instance, found that high school GPA "closely track[s]" college GPA, and that students with strong grades but lower test scores went on to outperform peers with the opposite profile — higher test scores but weaker grades. ACT has responded to this type of research by asserting that test scores provide valuable additional information on college applicants, above and beyond what can be gleaned from high school grades alone.