The Academic Performance Index (API)

May 2006
The API Base-Growth cycle
Goals for school improvement

The API has been the centerpiece of California’s program to hold schools accountable. It compares how a school’s students as a whole perform relative to other schools in California.

However, since the enactment of the federal No Child Left Behind Act (NCLB) in 2002, the API has taken a back seat to NCLB’s “adequate yearly progress (AYP)” approach. A school’s API score is only one measure of its performance under NCLB. But because the API system is somewhat familiar to the public, includes a statewide ranking of schools, and focuses on improvement, it remains an important part of California’s accountability system.

Under the API system, the vast majority of California schools have received an API score for the school as a whole and for each “numerically significant” subgroup of pupils categorized by ethnicity, poverty, and English learner and Special Education status. An API score is a one-number summary of scores on state-required standardized tests. Various tests receive different weights in the index. To be “numerically significant,” a subgroup must have 100 students or have 50 students that constitute 15% of the school’s student body.

At first not all schools received API scores. An insufficient number of students tested, or a student body with a majority of at-risk students (typically found in continuation high schools, court schools, or other alternative schools), excluded a school from the API system and qualified it for the “Alternative Schools Accountability Model.” Further, if a school had irregularities in the test administration or experienced a significant demographic change from the previous year, it did not get an API score. Now, to meet federal No Child Left Behind (NCLB) requirements, California gives API scores to all schools with 11 or more test-takers who have been enrolled in the school since the October California Basic Educational Data System (CBEDS) data-collection day.

The API Base-Growth cycle
The API system is organized into two-year cycles, with a “Base” score for the first year and a “Growth” score for the second year. (The Base and Growth scores can be thought of as “before” and “after” snapshots.) In the early part of the calendar year, each school receives a Base score between 200 and 1000 based on its students’ performance on tests given the prior spring.

The school as a whole and its subgroups are also given growth targets. The Growth score—based on test scores from the following spring—is released in the fall. A school’s Growth score indicates whether the school met its growth targets and were originally used to determine eligibility for awards or interventions. The calculation of Base API scores has changed from one year to the next as new tests have routinely been incorporated into the index. However, the California Department of Education (CDE) makes adjustments to reduce fluctuations in the schools’ Base scores because of these new tests. The CDE likens this adjustment to that made to the Dow Jones Industrial Average when new stocks are included in that index. However, in each API cycle, the Growth API is calculated in the same way as the Base API, ensuring that Base/Growth results are comparable.

Schools are ranked annually based on their Base API scores. Schools are ranked in two ways, but only with schools of the same type—elementary, middle, and high. First, schools are ranked with all others in the state.

Second, they’re ranked with the 100 most similar schools in terms of challenges, based on student characteristics, teachers’ credentials, whether they operate year-round, and other factors. This second “similar schools” ranking recognizes that students’ test scores are strongly associated with factors such as family income, parent education level, and students’ knowledge of English. As a result, schools with large numbers of students from low-income families, for example, tend to have lower API scores. Partly because of the problems in comparing schools with very different student populations, the state created the similar schools rankings. In an attempt to make this ranking more meaningful, the state for the first time included in the 2005 Base API how many students are enrolled in gifted programs, have disabilities, are migrants, attend small classes, and have mastered English despite being non-native speakers. It also took into account the grade configuration of schools, such as whether a middle school serves sixth- through eighth-graders or just seventh- and eighth-graders. Some schools experienced significant changes in their rankings when these new factors were considered.

For both types of rankings, schools are clustered into 10 groups of roughly equal size known as “deciles,” with the bottom 10% of each school type belonging to Decile 1, the second lowest 10% to Decile 2, and so on. A shorthand has developed around these rankings: a “7/5” school, for example, would be a school that received a state decile ranking of 7 and a “similar schools” decile ranking of 5.

Small schools—those with fewer test-takers—technically are part of the Alternative Accountability system. Their API scores come with an asterisk to indicate that the scores may not be as accurate an indicator of the schools’ “true” performance as it is for larger schools. Although small schools do not affect the rankings, they are given the ranking associated with their API scores.

Initially the API score was based on student test results on the Stanford-9, a basic-skills test. Currently the California Standards Tests (CSTs) in English language arts (ELA) and math play the dominant role in the API calculation for elementary and middle schools, with science CSTs having a smaller role. For high schools, CSTs in ELA, math, science, and social studies as well as ELA and math results from the California High School Exit Exam (CAHSEE) make up the API calculation. Another basic-skills test, the CAT/6, which replaced the Stanford-9, plays a smaller role in the API calculation for elementary and middle schools. In 2004–05 the CAT/6 was no longer part of the high school API. (See API composition in 2005-06 cycle for a graphical depiction of these calculations.)

Goals for school improvement
Computing a school’s (and subgroup’s) API score involves sorting students’ test scores into five performance levels. An API score is basically a summary of the distribution of scores among the five performance levels, with various subjects and tests receiving various weights in that calculation. The state set 800 as the target score for all schools. If all students in a school score in the top performance band on all subtests, the API score for that school would be 1000.

To achieve growth in its API score, a school (or subgroup) needs to have a greater percentage of its pupils score in higher performance bands. The API formula rewards growth from the bottom of the performance distribution upward more heavily than growth from the middle upward. This creates an incentive for a school to work with its lowest-performing students.

For a school with a Base API score below 800, the annual growth target is 5% of the difference between 800 and its Base score. (The idea is that a school should be able to close the gap between its current score and the state goal by 5% in one year. The farther a school’s score is from the goal, the greater its growth target.) For example, a school with a Base score of 500 would have a growth target of 15 because that is 5% of the difference between 800 and 500. The growth target for schools with Base scores of 800 and above is to maintain their scores at 800 or above. Subgroup growth targets are generally 80% of the school’s target. So for a school with a Base score of 500, the subgroup targets would be 12 (80% of 15 = 12). Beginning with the 2006 Base API (released in March 2007), all subgroups as well as the school as a whole will be expected to improve by at least 5% of the difference between each of their scores and 800 or a minimum of 5 points, whichever is greater. For example, if English learners at a school scored 700 in the 2006 Base API, their growth target score in 2007 would be 705 (800 - 700 = 100; 100 x 5% = 5; 700 + 5 = 705). If the overall 2006 Base API for their school is 760, the schoolwide growth target would be 765 because of the 5-point minimum requirement.

The API does not reflect individual students’ test-score growth. It summarizes a school’s performance in one year (Base) and compares it to the school’s performance in the following year (Growth), but the groups of students in each year are different. For example, in a K–5 elementary school, the Base API would include scores of fifth graders who would not be attending the school during the Growth API year.

To see the API score for schools throughout the state, go to the Education Data Partnership website: www.ed-data.k12.ca.us.