Dynarski points to research conducted by alumnus Joshua M. Hyman (Ph.D. '13), a faculty member at the University of Connecticut. Hyman studied the result of the state of Michigan's requirement, beginning in 2007, that all high school juniors take the ACT college admissions exam.
"For every 1,000 students who took a college exam when it was optional, and scored high enough to attend a selective college, another 230 high scorers appeared once the test was mandatory," writes Dynarski. "For low-income students, the effect was larger: For every 1,000 students who scored well on the optional test, an additional 480 did so on the mandatory test."
Although the effect was not huge, it could still help to close the achievement gap for students from lower socio-economic backgrounds, says Dynarski.