Ziomek, R. L., & Andrews, K. M. (1996). Predicting the college grade point averages of special-tested students from their ACT assessment scores and high school grades . American College Testing Program. https://www.act.org/content/act/en/research/pdfs/predicting-the-collegegradepointaveragesofspecial-testedstudents.html

Also available online in ERIC database at https://eric.ed.gov/?id=ED405357

The test was administered under an extended-time condition (up to triple the standard allotted time condition).

Over 611,000 student records from 1,006 participating institutions were searched resulting in a total of 2,959 special-tested students matched with valid college GPAs, predicted GPAs, and complete ACT test results. Three groups of identified disabilities had a sufficient number of students to warrant further analyses: attention-deficit disorder (ADD; n=480); dyslexia (n=526); and learning disabilities (n=1,258).

The American College Test (ACT) served as the dependent variable for this extant data set analysis.

The correlation of predicted with actual college GPAs was largest for the attention deficit group regardless of the combination of test package and extended time guideline (r=.45). The correlation between predicted and actual college GPAs is lowest for students diagnosed as learning disabled who were administered the cassette tape under the three hour per test timing guideline (r=.27). The average error of prediction was negative for all but one of the conditions analyzed—students diagnosed as dyslexic who were administered the cassette version with up to three hours to complete each test had as mean prediction error of .06. Students diagnosed as having ADD had the largest 'relative' over-prediction bias.