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Randomized Trials Flourish in Developing Countries

Outside agencies, including MIT lab, help fund studies yielding insights.

In 1997, the Mexican government launched a bold anti-poverty experiment in seven poor, rural states. The government’s idea was to give cash payments to mothers who met two key conditions: They had to enroll their children in school and take them for regular health checkups.

The program, known by the Spanish acronym PROGRESA, worked. In 18 months, school enrollments increased, families reported eating more nutritious meals, and children grew healthier. What was just as remarkable was that Mexican authorities could document those improvements through a massive, randomized experiment that involved 24,000 households and eminent researchers from around the world.

“It affected some people’s attitudes about randomized experiments like the Tennessee STAR study did in the United States,” said Patrick J. McEwan, an economist at Wellesley College in Wellesley, Mass. He referred to a landmark class-size experiment, called Student/Teacher Achievement Ratio or STAR, that touched off a spate of state and national programs in the 1990s that were aimed at creating smaller classes...