This year, three economists who have devoted their careers to studying the alleviation of poverty in developing countries won the Nobel in economics (which, yes, we know, is not a real Nobel, but it’s still the most prestigious prize in the discipline). All three are known for their experimental approach to the issue. Two of them, Esther Duflo and Abhijit Banerjee, are leaders of the Abdul Latif Jameel Poverty Action Lab (J-PAL), an organization that has been remarkably successful in spreading this methodology.

In a paper published in 2018, the economist Arthur Jatteau looked at just how J-PAL became so influential: its use of randomized controlled trials. As a method for addressing problems related to poverty, RCTs operate much the way they do in medicine. For example, researchers hoping to improve children’s school attendance might provide de-worming treatments to one set of students and see how they perform compared with an untreated control group.

This is not a new concept, Jatteau writes. Experiments like this were first done in the 1920s. But they’ve become far more common since J-PAL started up in 2003. Important global institutions, from major research universities to the World Bank, have adopted randomized trials as a best practice. The concept has also received glowing treatment in the media and been embraced by political leaders involved in economic development.

This growth has occurred despite some criticism within economics. For example, Angus Deaton—winner of the 2015 economics Nobel—has written that truly randomized experiments are difficult to achieve in the complex field of economic development. Deaton argues that projects narrow enough to be scientifically rigorous may be too narrow to provide clear guidance for large-scale interventions.

So, why have randomized trials spread so fast? Jatteau writes that one crucial part of the picture is the structure of J-PAL itself. Looking at J-PAL-affiliated researchers, Jatteau finds that they are among the elite of the field of economics. Forty-five percent got their PhDs from Harvard or MIT, and a strong majority had a doctorate from a top U.S. or European school. They are also far more likely to work for these top schools than the average academic economist. Jatteau writes that this elite character may have helped randomized trials to spread for two reasons. First, the prestige of these top researchers may rub off on the method itself. Second, other economists may be eager to join a field populated by so many professionally successful researchers.

At the same time, the network of J-PAL-affiliated researchers is tight, with many of its members coauthoring papers together. A few of them, including Duflo and Banerjee, had particularly large numbers of coauthors within the network, as well as prestigious professional positions, making them leaders who help hold the field together. “Here, a highly connected network works as a guarantee to keep methodological principles the same,” Jatteau writes.

Jatteau’s work may help explain why Duflo and Banerjee are such influential proponents of randomized trials—not just due to their own work but because of the strong network they’ve created to support the method.