Studies combined in a meta-analysis often have differences in their design and conduct that can lead to heterogeneous results. A random-effects model accounts for these differences in the underlying study effects, which includes a heterogeneity variance parameter. The DerSimonian-Laird method is often used to estimate the heterogeneity variance,…

To fulfill its mandate and its potential the National Assessment of Educational Progress (NAEP) must be a multi-content annual assessment of priority learning areas. This report describes a procedure under which measures of attainment can be charted over time in a broad range of skill domains, on item-invariant item response theory scales, using…