In this paper, the authors examine some of the ways that different types of non-equivalent comparison groups can be used to strengthen causal inferences based on regression discontinuity design (RDD). First, they consider a design that incorporates pre-test data on assignment scores and outcomes that were collected either before the treatment…

Over the past several years, the authors have been developing an instructional technology, called Teachable Agents (TA), which draws on the social metaphor of teaching to help students learn. Students teach a computer character, their "agent," by creating a concept map of nodes connected by qualitative causal links. The authors hypothesize that…