High-quality preschool programs are heralded as an effective policy tool to promote the development and life-long wellbeing of children from low-income families. Yet evaluations of recent preschool programs produce puzzling findings, including negative impacts, and divergent, weaker results than were shown in demonstration programs implemented in…

This paper seeks to raise awareness among educational researchers and practitioners of some significant weaknesses and internal contradictions of randomised control trials (RCTs). Although critiques throughout the years from education scholars have pointed to the detrimental effects of this experimental approach on education practice and values,…

EBP -- evidence-based policy and practice -- has generated intense controversy. A rough continuum of positions can be discerned: At one pole are "tough-minded" commentators distinguished by their support of EBP; however, there are serious internal differences in this camp, for some regard randomised field trials (RFTs) as the gold…

Within evidence-based education, results from randomised controlled trials (RCTs), and meta-analyses of them, are taken as reliable evidence for effectiveness -- they speak to "what works". Extending RCT results requires establishing that study samples and settings are representative of the intended target. Although widely recognised as…

In the past few decades, we have seen a rapid proliferation in the use of quasi-experimental research designs in education research. This trend, stemming in part from the "credibility revolution" in the social sciences, particularly economics, is notable along with the increasing use of randomized controlled trials in the strive toward…

Research has shown that teacher effectiveness is the most important school-based factor that influences student outcomes, including student achievement. Studies have also shown that there is substantial variation in teacher effectiveness, such that some teachers improve student outcomes at a much faster rate than others. The strong influence of…

Purpose: The past decade has seen considerable debate about how to best evaluate the efficacy of educational improvement initiatives, and members of the educational leadership research community have entered the debate with great energy. Throughout this debate, the use of randomized experiments has been a particularly contentious subject. This…