January 18, 2018

Randomized Evaluation

What is a Randomized Control Trial?

The same type of studies used to test new drugs and treatments in medicine, randomized control trials (RCTs) are often referred to as the “gold standard” of empirical research methods.

An RCT tries to remove, as much as possible, the effects of countless background factors—things like gender, age, education, knowledge, etc.—that might also drive the outcomes in question.

A good study design removes all those other factors by randomly selecting some people into one group that encounters the intervention and then leave the rest of the population to experience the status quo—or rather, not encounter the intervention.

By creating two randomly selected groups this way, researchers can reliably test whether those exposed to the intervention have different outcomes than those who were not. Because of the randomization we can attribute those different outcomes to the intervention itself and not some background factor.

RCTs have already transformed best practices in fields beyond medicine, including global development and other social sciences.

More on randomized evaluation

Many scholars and institutions have developed great resources about the transformative power of randomized evaluation. If you’d like to learn more about the field, we recommend the following:

Introduction to randomized evaluation
Our colleagues at the Abdul Latif Jameel Poverty Action Lab (J-PAL) have created great materials to help you learn more about how randomized evaluation works and why it’s important. In particular, we suggest their introduction to RCTs and RCT video.

The J-PAL North America Evaluation Toolkit is a comprehensive guide for researchers and research staff interested in designing and implementing randomized evaluations. The full set of materials is available on a dedicated website.

Conducting RCTs:
Coalition for Evidence-Based Policy
Conducting Randomized Controlled Trials With Offenders in an Administrative Setting,” by Eileen M. Ahlin.

Benefits of RCTs:
Better LATE Than Nothing: Some Comments on Deaton (2009) and Heckman and Urzua (2009),” by Guido W. Imbens.
Coalition for Evidence-Based Policy
Innovations for Poverty Action (IPA)