scientific knowledge is needed about educational interventions to promote its use in decision making.
In order to generate a rich store of scientific evidence that could enhance effective decision making about education programs, it will be necessary to strengthen a few related strands of work. First, systematic study is needed about the ways that programs are implemented in diverse educational settings. We view implementation research—the genre of research that examines the ways that the structural elements of school settings interact with efforts to improve instruction—as a critical, underfunded, and underappreciated form of education research. We also believe that understanding how to “scale up” (Elmore, 1996) educational interventions that have promise in a small number of cases will depend critically on a deep understanding of how policies and practices are adopted and sustained (Rogers, 1995) in the complex U.S. education system.10
In all of this work, more knowledge is needed about causal relationships. In estimating the effects of programs, we urge the expanded use of random assignment. Randomized experiments are not perfect. Indeed, the merits of their use in education have been seriously questioned (Cronbach et al., 1980; Cronbach, 1982; Guba and Lincoln, 1981). For instance, they typically cannot test complex causal hypotheses, they may lack generalizability to other settings, and they can be expensive. However, we believe that these and other issues do not generate a compelling rationale against their use in education research and that issues related to ethical concerns, political obstacles, and other potential barriers often can be resolved. We believe that the credible objections to their use that have been raised have clarified the purposes, strengths, limitations, and uses of randomized experiments as well as other research methods in education. Establishing cause is often exceedingly important—for example, in the large-scale deployment of interventions—and the ambiguity of correlational studies or quasi-experiments can be undesirable for practical purposes.
In keeping with our arguments throughout this report, we also urge that randomized field trials be supplemented with other methods, including in-depth qualitative approaches that can illuminate important nuances,