The API is a single-number indicator of the performance of a school's students on state tests. Based on their API scores, schools' performance is ranked from 1 (lowest) to 10 (highest).
Each spring, schools receive a "Base API" between 200 and 1,000 and a growth target. The following fall, schools receive a "Growth API," which is based on spring test scores. APIs are calculated for the entire school and for "numerically significant subgroups" based on ethnicity, economic status, disabilities, and the ability to speak English.
Scores from several tests (see below) are used to compute schools' and subgroups' API scores. Different tests have different weights, and these weights have been altered as new tests have been included in the index during recent years. The weights are always the same for the Base and Growth scores within one API cycle, however. (API scores are in two-year cycles, with Base API scores coming out in the first school year and Growth API scores in the second year.)
Until the 2004/2005 cycle, each subject (English language arts, math, science, and social science) had a uniform weight for schools at each level (elementary, middle, and high). Now the weights can vary somewhat from school to school within the same level and API cycle, depending on which tests are taken and the percentage of students taking each test.
The charts to the right, adapted from the CDE's 2009-10 Academic Performance Index Reports information Guide, show the weight of each component for "typical" elementary, middle, and high schools in the 2009/2010 cycle.
Tests included in the API:
- California Standards Tests (CSTs): English language arts (ELA), math, science, and social studies;
- California High School Exit Exam (CAHSEE)-grade 10 only: ELA and math
Scores from the California Alternate Performance Assessment (CAPA), a test for students with severe disabilities, are a small part of some schools' API scores.
Note: The sum of the percentages may not equal 100% because of rounding.
Data: California Department of Education (CDE)