The University of North Carolina’s Board of Governors made admissions effectively test optional — but North Carolina public school students still take the ACT in 11th grade; it’s required by North Carolina law:
This set up an interesting natural experiment, since the North Carolina Department of Public Instruction collected these ACT scores from high schools and shared them with the UNC System. Therefore, we know the ACT scores of all public-university students who applied to UNC-Chapel Hill and NC State during the test-waiver period, regardless of whether they submitted those scores for use in the admissions process.
At both NC State and UNC-Chapel Hill, the test scores of students who chose to submit them as part of the admissions process were significantly higher than those of non-submitters.
And these discrepancies persist among admitted students. In 2022 (the year for which the best data exist), among admitted UNC-Chapel Hill freshmen, test submitters had a median ACT score of 29. Non-submitters had a median ACT score of 25. At NC State, the respective scores in the same year were 27 and 22. These are meaningful differences.