What Isn't There Matters: Attrition and Randomized Controlled Trials

Home Visiting Programs OPRE Report #2014-49
Publisher: Washington, DC: U.S. Department of Health and Human Services, Administration for Children and Families, Office of Planning, Research, and Evaluation
Aug 29, 2014
Sarah A. Avellar and Timothy Silman

A randomized controlled trial (RCT) offers a highly credible way to evaluate the effect of a program. However, a strong design can be offset by weaknesses in planning or execution. One common problem that weakens the conclusions of RCTs is attrition, or missing data. This brief describes what attrition is, why it matters, and how it factors into the study ratings in the HomVEE review.