“If you give everybody an A, either people are not going to take it seriously or those who do take it seriously might get the wrong impression,” Healy said. “When students receive grades, they’re receiving feedback on how well they did in their courses, if they put in an equal amount of effort [in] each one. And [if] they receive higher grades in some subjects, they logically come to the conclusion that they are good at certain things. It wouldn’t normally occur to them that they happened to receive a grade that was out of line."

Grade inflation is more prevalent now at private institutions than it is at public ones, according to the study. The mean GPA for both private and public schools in the 1930s was 2.3, or a C+. That number for both types of institutions increased at the same rate until recently. Today, the average GPA at private universities is 3.3, a B+, while that at public colleges is 3.0, a B.

A 2013 study conducted by the University of North Texas’s Department of Economics might help explain the forces behind recent grade inflation, suggesting that several key players could be responsible for the overall trends. For one, the study shows that classes in certain subject areas are more prone to inflation than others. English, music, and speech courses experienced higher rates of inflation compared to those in math and chemistry, for example.



Class size also appears to be a factor. One theory is that departments with smaller student-faculty ratios have a greater tendency to exaggerate grades because those instructors have less job security than their colleagues in larger-scale college divisions. “Let’s say my department finds out that we give far fewer As than some other department that we’re competing against for students,” Healy said. “That may give an incentive for faculty to increase their grades.”



The type of degree program could also influence the extent to which professors overstate students’ grades. Inflation was more prevalent among Ph.D. departments, for example, than it was among lower-level programs, according to the study, which looked at data between 1984 and 2005. The instructor’s gender could be a factor, too: Inflation is much higher among female educators than it is among their male counterparts.



Meanwhile, student evaluations could incentivize instructors to give their pupils higher grades than they deserve in an effort to “buy” higher evaluation scores, the study says.



Whatever the cause, an analysis of average test scores—as well as literacy levels—over time confirms that rising GPAs are not a reflection of increasing academic achievement. Though standardized exams are certainly flawed measurements of intelligence, comparing trends in scoring with those in grades is revealing: Unlike average GPAs overall test scores have remained relatively steady over time, demonstrating that the grade inflation is artificial. Graduate literacy has also kept constant; the 2003 National Assessment of Adult Literacy found that average literacy hasn’t changed since 1992.