What is a Percentile?
In the charts and graphs on the following pages, we present comparative data about the school systems on your list of similar school systems on a national percentile basis. In this way, "average" is always "average."
A percentile shows how a single school system may be compared to all other school systems in the country. Ninety-nine (99) is the highest percentile and one (1) is the lowest percentile.
Percentiles representing a school characteristic are developed by arranging the average results from all school systems in the county (15,890) from lowest to highest. Then these 15,890 school systems are placed into 99 separate groups (about 160 per group) from lowest to highest. Each group represents one percentile. In this way any school system can be compared on the same characteristic to all other school systems in the country.
For example, a percentile of 99 in the area of test scores (say the college entrance exams, the ACT or the SAT, for example) for one school system may be compared to a test score percentile of 1 for another school system. This means that the school system in the 99th percentile is among the top 160 school systems in the country on test scores whereas the school system in the 1st percentile is in the bottom 160 school systems in the country, taking into consideration the numbers of students in each school system who take the test.
"Top" or "bottom" do not necessarily mean "good" or "bad." For example, parents may want high test scores but low pupil/teacher ratios.
On the following graphs and tables, we show you how your selected school system and each of the school systems in the set of similar systems compares to all other school systems in the nation on a percentile basis. It may be helpful to keep in mind that the 50th percentile is always the "middle " of the scale, and represents the "average" percentile ranking, on a scale from 1 to 99.