This policy brief examines the graduation efficiency index (GEI), a measure developed by the University of Washington to enable the state to measure a student's or institution's efficiency in graduation. The study compares the GEI index with time-to-degree, the most widely used related measure, and finds that the latter does not measure student efficiency in degree pursuit regardless of enrolled time, nor does it reflect the current reality that only a minority (25 percent at Washington State University) of students graduate in four years. By contrast, the GEI which uses a formula that accounts for credits earned toward a degree compared to credits required for a particular degree, is a better measure of efficiency because it does not focus on elapsed or enrolled time but on actual credits earned. Limitations to the GEI are also noted, such as its retrospective character, its inability to consider effectiveness as well as efficiency, its vulnerability to manipulation, and its limitations when applied to transfer students' efficiency. The paper concludes that one cannot measure efficiency with a time-to-degree tool, or measure the value of extra credits earned with an efficiency index, and suggests that institutions use both measures to evaluate the institution's success in graduating students. (DB)