In calculating these ratings, GreatSchools analyzed the 2011-2012 Measurements of Student Progress (MSP), End-of-Course (EOC), and High School Proficiency Exam (HSPE) reading, writing, math and science results and compared them to the standardized scores of all Washington schools with the same grade levels.
If there are no GreatSchools Ratings for a school, the school's test results were either not reported or incomplete. The different student groups are identified by the Washington Office of Superintendent of Public Instruction; if there are fewer than 10 students in a particular group in a school, data is not reported for that group.
Keep in mind that when comparing schools using GreatSchools Ratings, it's important to factor in other information, including the quality of each school's teachers, the school culture, special programs, etc.
GreatSchools Ratings cannot be compared across states, because of differences in the states' standardized testing programs.