The present article considers a fundamental question in evaluation research: "By how much do program effects vary across sites?" The article first presents a theoretical model of cross-site impact variation and a related estimation model with a random treatment coefficient and fixed site-specific intercepts. This approach eliminates…

This study investigated how middle school students leverage information about bound Latin roots (e.g., "voc" in "advocate" and "vociferous") to infer meanings of unfamiliar words, and how instruction may facilitate morphological analysis using roots. A dynamic assessment of morphological analysis was administered to…

This study investigated how middle school students leverage information about bound Latin roots (e.g., voc in "advocate" and "vociferous") to infer meanings of unfamiliar words, and how instruction may facilitate morphological analysis using roots. A dynamic assessment of morphological analysis was administered to 29 sixth…

Using exogenous characteristics to identify endogenous subgroups, the approach discussed in this method note creates symmetric subsets within treatment and control groups, allowing the analysis to take advantage of an experimental design. In order to maintain treatment--control symmetry, however, prior work has posited that it is necessary to use…

Personalized e-learning implementation is recognized as one of the most interesting research areas in the distance web-based education. Since the learning style of each learner is different one must fit e-learning with the different needs of learners. This paper presents an approach to integrate learning styles into adaptive e-learning hypermedia.…

This "What Works Clearinghouse Procedures and Standards Handbook (Version 3.0)" provides a detailed description of the standards and procedures of the What Works Clearinghouse (WWC). The remaining chapters of this Handbook are organized to take the reader through the basic steps that the WWC uses to develop a review protocol, identify…