Our Ratings Methodology

For all rating types, schools are rated against other schools of similar grade levels: either elementary/middle schools or high schools. 

Want to know more about our data sources? Click here.


Math: The math score represents the percent of students performing math on grade level (proficient or advanced), as measured by the most recently available standardized testing data. This raw score is then compared to other schools in Philadelphia. See Data Sources.

Reading: To calculcate the reading academic rating,  GreatPhillySchools used the most recent standardized-test data available (see Data Sources). Based on the percent of students reading on grade level (as measured by standardized tests).

GPS then created a list of all schools sorted by their proficiency scores for both subject areas tested, high to low. Deciles were created by dividing the range of scores (highest score to lowest score) into 10 equal increments. All schools scoring in the top increment were assigned a 10 rating, in the second-highest increment a 9 rating, and so on.

All public schools take Pennsylvania System of School Assessment tests (PSSAs). Catholic schools take different tests called the TerraNova 3rd Edition. GreatPhillySchools used grade mean equivalent scores provided by TerraNova through the permission of the Archdiocese of Philadelphia as comparable measures of student proficiency, so that Catholic schools could be rated on the same scale as public schools. GPS counted the percentage of students in a Catholic school scoring at the grade mean equivalent or higher as the percent proficient.

Attendance: All public schools are required to report average daily student attendance to the state Department of Education. Catholic schools report the same statistic to the Archdiocese Office of Catholic Education. GreatPhillySchools sorted all schools by their average daily attendance, high to low, and then applied the same deciling methodology described above to produce ratings of 1 to 10.

Safety: All public schools are required to report a variety of disciplinary incidents to the state Department of Education. Catholic schools collect similar information and report it to the Office of Catholic Education. GreatPhillySchools gathered for each school the number of incidents reported: These can include any behavior that violates a school's educational mission or climate of respect or jeopardizes the intent of the school to be free of aggression against persons or property, drugs, weapons, disruptions and disorder. Reportable incidents include serious criminal violations such as rape and aggravated assault, as well as much broader types of violation such as bullying, fighting and minor altercations. Each school’s total incident count was divided by 100 students, so that safety scores would be proportional. Schools were ranked high to low, and again the range was divided into deciles. However, in this case the deciles were established on a logarithmic scale, rather than in equal-sized metric increments. On a logarithmic scale, each successive increment is exponentially larger. This method was chosen for safety because it allows for greater articulation of differences at the low end of the scale. On a standard increment scale, a school with four incidents per 100 students might be rated the same as a school with one incident per 100, even though that represents four times as many incidents. A 10 rating for safety means a school fell into the band of schools with the fewest number of incidents.

View more details on how our safety ratings are collected.

College Bound: A nonprofit institution called the National Student Clearinghouse tracks all students who are enrolled in 2-year and 4-year colleges in the United States and reports on this data to colleges and universities, student-loan institutions and high schools. GreatPhillySchools obtained Clearinghouse records, aggregated by high schools, for all 2012 graduates of Philadelphia high schools to create a ranking of high schools by the percentage of graduates who were enrolled in college within one year of their high-school graduation. This range from high to low was then divided into equal-sized increments to create ratings from 1 to 10, with 10 representing the highest college enrollment rates.

Achievement Gap: To calculate an achievement gap, GPS measured the proficiency gap between students classified as “economically disadvantaged” in state data and those not classified that way. Only schools with at least 40 students in each subgroup receive an achievement gap rating. The gap is calculated as the number of percentage points between the two groups on the average academic proficiency score described above. Then all schools receiving a gap score are ranked high to low and deciled according to the increment method.

Overall Quality: This is a combination of schools’ academic, college bound (for high schools), attendance and safety ratings. To assign an overall rating for an elementary school, GPS averaged together the decile ratings for that school on a weighted basis: 60% weight for the academics (30% for math and 30% reading), 30% weight for the attendance rating and 10% for the safety rating. For high schools: 30% for the academic rating (15% for math and 15% reading), 30% for the college bound rating, 30% for the attendance rating and 10% for safety. Schools were then ranked according to their weighted overall averages and deciled in equal-size increments from the top end to the bottom end of the range.

For more detail on the sources of the data used to determine school ratings, see GPS Data Sources.

High School Graduation Rates: For public high schools, this statistic is listed on each school’s profile page. It represents the school’s four-year “cohort” graduation rate, which is tracked by the state. The cohort rate represents the percentage of 9th graders who graduate from the same school four years later, after subtracting out students who transferred to other schools and adding in those students who transferred in.

Data collection and analysis for GreatPhillySchools was managed by the Philadelphia School Partnership in consultation with Data Partners LLC, a data analytics consulting firm with significant experience analyzing and modeling student and school performance data. Guidance and assistance was also provided by the Pennsylvania Department of Education, McGraw-Hill’s CTB division (producer of the TerraNova) and Frontier 21 Solutions, an education research company.

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