New AEM study analyzes 50,000+ test items for PowerSchool
An AEM white paper released today finds that the vast majority of PowerSchool's approximately 50,000 test items are of high quality.
AEM conducted all appropriate classical item, item response theory (IRT), and differential item functioning (DIF) analyses on all items from both PS's Student Growth Assessments (SGAs) and in its Item Bank (IB) with sufficient student responses generated during the 2015-2016 school year.
Major findings include
- 95 percent of SGA items have Cronbach alphas of .8 or higher, which suggests uniformly high reliability.
- IRT models show that both SGA and IB items vary in difficulty, with a roughly normal distribution of item locations centered around a location of 0.
- The same IRT models show that 83 percent of SGA items and 82 percent of IB items do a good to excellent job of discriminating between students of different ability levels.
- 90 percent of SGA items show no DIF based on gender. 92 percent show no DIF based on race/ethnicity.
Please download the full white paper here.