Estimates a model allowing researchers to determine how much achievement on a 10th-grade standardized test can be explained by observable schooling resources and unobservable school, teacher, and class effects. Although few observable variables are significant test-score determinants, unobservable effects seem important in explaining student…

The stability of Rasch test item difficulty parameters was investigated under varying conditions. Data were taken from a mathematics achievement test administered to over 2,000 Australian students. The experiments included: (1) relative stability of the Rasch, traditional, and z-item difficulty parameters using different sample sizes and designs;…