Data on school performance is in high demand among the parents of school age children and real estate professionals working to fully communicate a particular property's value (i.e., "the schools are wonderful"). This data is also widely used in political campaigns. Since the Public Schools Accountability Act passed in 1999, the California Department of Education (CDE) has been responsible for administering the statewide Standardized Testing and Reporting (STAR) program and reporting the results. Each year, California public school students at the elementary, middle and high school levels are tested across multiple subject areas. The CDE processes the results into a school wide Academic Performance Index (API) ranging from a low of 200 to a high of 1000.
Yesterday, California State Superintendent of Public Instruction Jack O'Connell released the 2009-2010 Base API report for California schools. The CDE houses Base API and Growth API reports dating back to 1999. Also available are dBase and text format data files of the information used to calculate APIs, which developers can download to create customized databases. Here's a description of each report:
- Base API reports are released during the spring. Base API is calculated using the previous year's test results and is used to rank schools statewide as well as with 100 other similar schools that have comparable demographic characteristics. Ranks are reported in deciles such that "1" represents the lowest 10% of schools and "10" is reported for the highest performing schools. Additionally, demographic data is used to calculate which minorities (ethnicities, socioeconomically disadvantaged, disabled or English learners) are statistically significant and to establish target growth goals for the following year in accordance with the Closing the Achievement Gap Initiative.
- Growth API reports become available in the fall. Growth API is determined based on the same parameters as the Base API but uses test scores from the current year. By subtracting the Base API from the Growth API, schools find out whether overall school performance has increased or decreased since the previous year and whether the growth target has been met. Growth APIs are also calculated for each statistically significant minority group to find out whether specific growth targets were reached as well.
For those who live outside of California, most states departments of education also calculate API rankings or similar indices. Several important considerations to keep in mind when reviewing API reports:
- Cross-sectional data is calculated to measure annual growth of a school as a whole, rather than individual student performance as they age.
- The indicators and test weighting used for API calculations changes from cycle-to-cycle, so Base and Growth APIs may be compared from the same cycle only. However, evaluating the change in APIs across reporting cycles will yield appropriate comparison.