We know the positive effects of Georgia’s HOPE Scholarship: An increase in high school rigor. More academically gifted students remaining in state for college. A rise in the quality of public campuses.

We know less about the negative effects. In two new studies, researchers at Georgia State University and Oklahoma State University suggest a negative consequence: fewer Georgia students pursing grueling science and math degrees.

Students need a 3.0 GPA to get and keep HOPE, which pays most of the tuition bills. For every 10 students who start a public college or university with the scholarship, only about four — 37 percent — hold onto it the entire time they are in school. At the University of Georgia, the percentage of students keeping HOPE through graduation is 48.5 percent. At Georgia Tech, it’s 37.3 percent.

No slack is cut for students in the hardest disciplines — the electrical engineering majors at Tech, or biochemistry majors at UGA — when their GPAs stumble to a 2.9.

The new studies raise a question that’s been asked in the past, but never resolved: Should Georgia re-calibrate HOPE to encourage students to enter high-demand STEM fields? Technology companies are complaining they have to import STEM workers or sometimes bypass Georgia because of the shallow pool.

So, we ought to be concerned the studies found merit-based scholarship programs reduce the likelihood a student will earn a degree in a science, technology, engineering and mathematics. One study looked only at HOPE, while the other examined merit-based aid programs across nine states. Researchers compared STEM enrollment before and after the states adopted merit-based scholarships, made comparisons with states with no merit aid programs, and evaluated the effect of merit aid.

The conclusion: Adopting a strong merit aid program reduces a state’s number of STEM graduates by 6.5 percent and possibly by as much as 9.1 percent. The decrease in the likelihood of earning a STEM degree as a result of a strong merit aid program was more dramatic for male students than for female students.

The Georgia-focused study found HOPE had its greatest impact on STEM majors at the three research universities, particularly Tech. “We found HOPE reduced the probability that Tech graduates earned a STEM major,” said study co-author David L. Sjoquist, a GSU professor of economics. “This could be they were less likely to declare a STEM major when entering college or were more likely to change majors from STEM to something else once they were enrolled.

“We don’t know the reason why HOPE reduced the likelihood of being a STEM major, so we can’t say that it was due to the fear of losing HOPE, but that is one possible explanation,” said Sjoquist. “Another possible explanation: High school students avoid hard subjects — math, science, etc. — to have a high school 3.0 GPA so they are eligible for HOPE. If so, they come to college less prepared and thus may choose a major other than STEM.”

Sjoquist offers two remedies to encourage students to pursue STEM degrees and retain them in the programs:

• Enable high school students to stick with killer science and math classes that threaten their GPAs by basing eligibility for HOPE on SAT or ACT scores.

• Once students are enrolled in college STEM programs, lower the GPA requirement to keep HOPE.

As a parent on my AJC Get Schooled blog said: “My son is in his second year as a chemical engineering major at Tech. He told me engineering majors who can’t keep HOPE change their majors to business. What is the point of taking scholarship money away from a kid who is taking really difficult classes and working his butt off? Do we really want him to leave chemical engineering and become another business major?”