Average Point Difference Measure (APD)
CCSA has created the Average Point Difference (APD) to help schools and parents better understand SBAC scale scores and interpret growth. APD is a measure that compares a school's SBAC scale scores by grade to the state standard for "met". The APD means that the average student in the school scored that many scale score points above or below the met standard.
We believe that rather than using a percent met or exceeded measure that incentivizes schools to only focus on "bubble students", the APD instead encourages schools to help each student raise his or her score as high as possible each year.
How is the APD calculated?
The Average Point Difference (APD) measure is averaged by grade and subject, enabling fair comparisons across all grade spans and subgroups. A school's average SBAC scale scores are compared across grade and subject to the minimum standard scale score for the achievement level "met" (see more on the SBAC scale score ranges). The difference between a school's actual average score and the met score is then weighted by the percent of test-takers in each grade. These weighted differences are averaged across subject and grade to obtain a single APD per school. Additionally, all schools with an APD is ranked to calculate a statewide percentile.
The APD calculation is based on publicly-reported achievement scores, as reported to the California Department of Education. CCSA does not produce APD percentiles for schools that are ASAM, Alternative, or have fewer than 30 valid scores.
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