A recently completed study by Michael Klein of the Brookings Institute and Michael Cancian of Tufts University, a veteran of recent U.S. military conflicts, explores the paradox that, since the inception of the all-volunteer force, the percentage of those with above-average intelligence who are serving in the military has dramatically increased while the percentage of officers with above-average intelligence has steadily declined. This finding is especially pronounced in the Marine Corps, in which the scores on the military’s General Classification Test (GCT) have shown an especially marked decline over the last 34 years: specifically,

1. Eighty-five percent of those taking the test in 1980 exceeded a score of 120, which was the cut-off score for officers in World War II. In 2014, only 59 percent exceeded that score.

2. At the upper end of the distribution, 4.9 percent of those taking the test scored above 150 in 1980 compared to 0.7 percent in 2014.

3. Over 34 years, the average score decreased by 6.6 percent, from 130.9 to 122.1.

4. Taken together, the 8.2-point drop in average score represents 80 percent of an entire standard deviation’s decline (from 10.5 in 1980 to 9.6 in 2014). In other words, today’s Marine officers scored nearly an entire standard deviation worse, on average, than their predecessors 34 years ago.

So, how is access to college linked to this decline in average intelligence among the Marines’ officer corps?

From the results of their study, Klein and Cancian have drawn the following conclusions:

“the decline in officer quality might actually have to do with the fact that more people are receiving college degrees than ever before: The authors note that the decrease of GCT scores over time correlates to an increase in the college participation rate during that same period.

“A four-year degree is required to become an officer. Therefore, the authors posit, as more people who may not have obtained four-year degrees in the past receive them, more people who would otherwise not be eligible for commissions become viable applicants. Because the decline concerns all college graduates, it has likely also impacted the other military services.”

Moreover, Klein and Cancian “also address claims that changing demographics in the military may be driving the decline in scores.” Specifically, the authors consider “the effects of a higher proportion of women and Hispanics in the force, as well as the military’s efforts to actively recruit more African-American officers.”

Their findings undermine “claims that affirmative action or changing demographics have played any role in declining officer quality: ‘We find, in fact, a positive association between African-American officers and mean GCT score, perhaps because recruitment efforts by the Marine Corps have attracted minority officers who are more qualified than the typical college graduate.”’  Moreover, they have found that “the proportion of Hispanic officers has no statistically significant impact on the decline in score.“

Klein and Cancian’s ful report is available at: http://www.brookings.edu/research/papers/2015/07/20-nber-military-officer-quality-volunteer-force–klein