Methods used to measure performance differences vary. Some simply examine outcomes, comparing grades or scores on concept inventories for male and female students at one point in time. Others make efforts to account for background and preparation, either through pre-and-post testing, or by including measures of prepattion in performance models (e.g. high school GPA, standardized tests, and prior college performance) [8]. Most studies of performance gaps have been narrow in scope, exploring single courses in individual subjects for limited periods of time. Comparison among these studies is complicated by their various contexts and analytic approaches