I can attest to the new Nobel winners’ role in reshaping the field of development economics. They certainly influenced me. All three were my teachers when I was in graduate school at Harvard starting in 1999. In those days the field was small enough that they taught a combined class for Harvard and M.I.T. students, and Mr. Kremer and Mr. Banerjee were among my advisers.

I have run randomized experiments in India, Uganda and elsewhere on topics such as how to improve child nutrition, protect forests, and reduce gender discrimination. Some of the interventions I have tested had beneficial effects, and others did not.

Learning early that a program has limited benefits is useful for the organization running it and the donors funding it. They can redirect their time and money elsewhere, or try to change the program to make it more effective.

But Mr. Kremer’s Kenya textbook study illustrates another value of discovering that a program falls short of its promise. This type of so-called null result, where the impacts of an intervention are indistinguishable from zero, can lead us to think differently and more creatively.

When Mr. Kremer and his colleagues looked at their data in more detail, they saw that textbooks did help the students whose test scores were very strong before the experiment began. That finding got the researchers thinking harder about what features of the Kenyan education system led to this pattern, he said.

The deep problem with the schooling system, Mr. Kremer believed, was that it was geared toward the top students. He speculated that this might have been a vestige of the colonial era, when access to education was mostly limited to children from relatively privileged families. Today, education is available to children from a much wider range of family backgrounds, but the curriculum has not been adapted enough, he said.