Abhijit Banerjee and Esther Duflo of M.I.T. and Michael Kremer of Harvard have devoted more than 20 years of economic research to developing new ways to study — and help — the world’s poor.

On Monday, their experimental approach to alleviating poverty won them the 2019 Nobel Memorial Prize in Economic Sciences. Dr. Duflo, 46, is the youngest economics laureate ever and the second woman to receive the prize in its half-century history.

In studying problems like education deficiencies and child health, the economists search for evidence about which interventions can resolve them, and seek practical ways to bring good treatments to scale.

“In just two decades, their new experiment-based approach has transformed development economics, which is now a flourishing field,” the Royal Swedish Academy of Sciences said in announcing the prize.