Multisite trials, in which individuals are randomly assigned to alternative treatment arms within sites, offer an excellent opportunity to estimate the cross-site average effect of treatment assignment (intent to treat or ITT) "and" the amount by which this impact varies across sites. Although both of these statistics are substantively…

Many recent studies have aimed to demonstrate that specific types of reading comprehension depend on different underlying cognitive abilities. In these studies, it is often implicitly assumed that reading comprehension is a multidimensional construct. The general aim of this study was to examine the dimensionality of a large pool of reading…

Measurement invariance (MI) is a property of measurement that is often implicitly assumed, but in many cases, not tested. When the assumption of MI is tested, it generally involves determining if the measurement holds longitudinally or cross-culturally. A growing literature shows that other groupings can, and should, be considered as well.…