What data is used in calculating GreatSchools Ratings?GreatSchools Ratings are based on the most recent available standardized test results for schools in each state. The results we use are typically the percentage of students scoring at or above the proficient level on the test in each grade and subject (e.g., grade 4/math) and each grade, subject and student category (e.g., grade 4/math/Hispanic students). The proficiency levels and student categories are defined by the state Department of Education.