The analytic approach used for this study combined two particularly strong quasi-experimental evaluation methods: an interrupted time series analysis and a comparison schools technique. In the interrupted time series analysis, measures of student performance in schools that implemented the intervention were compared with the performance of similar students in the same schools prior to the implementation. The difference between performance levels in the two groups is referred to as a “deviation from the baseline.” A second interrupted time series analysis was conducted for a group of comparison schools in the same district that have characteristics similar to those of the intervention schools. The difference between the deviations from the baseline in the intervention schools and the deviations from the baseline in the comparison schools represents the estimated impact of the intervention.
Four Project GRAD sites participated in the evaluation. These are: Atlanta, Georgia; Columbus, Ohio; Houston, Texas; and Newark, New Jersey.
Administrative records maintained by the districts provided data on key quantitative outcomes: standardized test scores, attendance, grade advancement, course-taking patterns, high school graduation rates, and dropout rates. Sources of qualitative data included classroom observations; interviews; and focus groups with key program operators, principals and teachers, district administrators, and community leaders.