He argued that policies in single-sex schools that emphasize the academic side of these variables explained virtually all of the test score differences between the two types of schools. Both males and females in single-sex schools also gained on attitudinal variables such as leadership behavior, but much less of this difference was explained by school variables. However, after controls were applied for attendance at a selective college, effects on young women's aspirations disappeared, leading the researchers to conclude that single-sex education may be an indirect influence that facilitates entry into a select college in the first place. The study found that girls educated in single-sex schools continued to hold less stereotypic views of gender roles into college. Analyzing data drawn from the Second International Association for the Evaluation of Educational Achievement, Lee and Lockheed found no significant gender gap between mathematics scores of Nigerian boys and girls, once other variables were taken into account.
Studies also concur that students perceive single-sex school environments to be more orderly.
These studies view policy and training interventions as particularly valuable. Other studies have not claimed positive achievement effects for single-sex programs. A critical look at single-sex education for girls. Sex differences in affecting outcomes. Paper presented at the annual meeting of the American Educational Research Association, Chicago.