How are the By Grade ratings calculated?
We start by calculating ratings for each grade/subject combination; then we average those ratings into the By Grade ratings you see on the page. The test results for all schools for a given grade/subject are sorted from low to high and divided into deciles, or 10% portions. The bottom 10% of schools get a rating of 1, the next 10% get a 2, on up to 10, which indicates the school’s result is in the top 10%. If there are several identical values that overlap from one rating decile to another, they are given the higher rating. Once ratings are established for all grade/subject combinations, each school’s ratings are averaged to create the By Grade ratings that you see on the page. For example, the rating shown for grade 4 is an average of that school’s ratings for each subject tested in grade 4. If the grade 4 rating is a 10, it means that, on average, fourth-grade students at the school performed better than 90% of the fourth-grade students whose test results were reported at schools sta
