Multisite trials, which are being used with increasing frequency in education and evaluation research, provide an exciting opportunity for learning about how the effects of interventions or programs are distributed across sites. In particular, these studies can produce rigorous estimates of a cross-site mean effect of program assignment…

In connection with the Omnibus Appropriations Act, 2009, GAO (Government Accountability Office) was required to study the What Works Clearinghouse (WWC), a federal source of evidence about effective education practices. Operating through a 5-year contract awarded by the U.S. Department of Education's Institute of Education Sciences (IES), the WWC…

Scale linking is the process of developing the connection between scales of two or more sets of parameter estimates obtained from separate test calibrations. It is the prerequisite for many applications of IRT, such as test equating and differential item functioning analysis. Unidimensional scale linking methods have been studied and applied…