|GreatSchools Ratings for Illinois|
In calculating these ratings, GreatSchools analyzed the 2011-2012 Illinois Standards Achievement Test (ISAT) and the Prairie State Achievement Examination (PSAE) reading, math and science results for the school and compared them to the ISAT and PSAE results for all Illinois 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 Illinois State Board of Education. If there are a small number of students in a particular group in a school, the state doesn't report test results 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.