The regression discontinuity design (RDD) has the potential to yield findings with causal validity approaching that of the randomized controlled trial (RCT). However, Schochet (2008a) estimated that, on average, an RDD study of an education intervention would need to include three to four times as many schools or students as an RCT to produce…

Randomized controlled trials (RCTs) are widely considered to be the gold standard in evaluating the impacts of a social program. When an RCT is infeasible, researchers often estimate program impacts by comparing outcomes of program participants with those of a nonexperimental comparison group, adjusting for observable differences between the two…

Randomized trials of educational interventions often face logistical hurdles (Cook, 2002). For example, sometimes they are prevented from reaching their full-term. This would happen if, as a condition of participation, subjects insist on receiving the treatment program within a certain timeframe. This timeframe may be shorter than the full-term…