The Atlantic discusses the strengths and limitations of randomized evaluations with Esther Duflo.  An excerpt:

Do free bed nets in some countries lead to more cases of malaria? Could anti-parasite pills raise school attendance in one country and have no effect in another? How cheap does preventative care have to be for low-income families to see the doctor?

There might not be a perfect way to answer these thorny questions on a country-by-country basis. But some leading scientists think the most rigorous answer comes from what they call "randomized controlled trials."

Esther Duflo is widely recognized as the world's leading advocate of randomized controlled trials in development economics. As a methodology, RCTs have been used for over a half-century in clinical medicine, where the effect of a drug or medical procedure is confirmed or denied in scientific experiments involving control and treatment groups. The use of RCTs to address global poverty is a phenomenon of the last decade, but it has caught on with the force of a paradigm shift in economics, public policy, and other disciplines.

For the full article, click here.