We present an aggregation scheme that increases power in randomized controlled trials and quasi-experiments when the intervention possesses a robust and well-articulated theory of change. Intervention studies using longitudinal data often include multiple observations on individuals, some of which may be more likely to manifest a treatment effect…

This paper describes the context, processes and issues experienced over 5 years in which a RCT was carried out to evaluate a programme for children aged 7-8 who were struggling with their reading. Its specific aim is to illuminate questions about the design of complex teaching approaches and their evaluation using an RCT. This covers the early…

Interest in variation in program impacts--How big is it? What might explain it?--has inspired recent work on the analysis of data from multi-site experiments. One critical aspect of this problem involves the use of random or fixed effect estimates to visualize the distribution of impact estimates across a sample of sites. Unfortunately, unless the…

This What Works Clearinghouse (WWC) topic report addresses reading interventions for students in grades K-3, including core reading curricula, programs, or products to be used as supplements to other reading instruction, programs that focus on staff development, and literacy software. The WWC review on beginning reading focuses on programs…