This study shows that residual variation can cause problems related to scaling in exponential random graph models (ERGM). Residual variation is likely to exist when there are unmeasured variables in a model--even those uncorrelated with other predictors--or when the logistic form of the model is inappropriate. As a consequence, coefficients cannot…

The present study investigates different approaches to adding covariates and the impact in fitting mixture item response theory models. Mixture item response theory models serve as an important methodology for tackling several psychometric issues in test development, including the detection of latent differential item functioning. A Monte Carlo…

This study addresses several methodological problems that have confronted prior research on the effect of class size on student achievement. Unlike previous studies, this analysis accounts for the hierarchical data structure of student achievement, where grades are nested within classes and students, and considers a wide range of class sizes…

This article finds the empirical review of the intellectual effects of family factors by Lala Carr Steelman wanting because (1) it is selective and incomplete; (2) it ignores systematic aggregate effects; (3) it imposes linear analysis on nonmonotone relationships; and (4) it disregards most of the confounds identified by Steelman as crucial.…

The author responds to criticism by R. B. Zajonc on a review of the extant literature on the intellectual consequences of sibship size and birth order. (Author/LMO)