Triple Differencing Bikes in India

In 2007 in an effort to increase the number of girls enrolled in school the government of Bihar in India gave each schoolgirl of age 14 a bicycle. The excellent Karthik Muralidharan and co-author Nishith Prakash set out to discover whether the program was effective. To jump to the conclusion they found that the program increased the enrollment of girls by 41% reducing the gender gap by almost half.

The reason for this post, however, is not the result–important as it is–but the two videos the International Growth Center made to explain Muralidharan and Prakash’s research methods. The first video explains the background of the research and then gives a very elegant explanation of triple-differences as an estimation strategy.

The second video explains that the researchers still weren’t completely happy that they had truly identified a causal effect (or perhaps the referees were not completely happy) so they hit on a complementary approach, looking for a dose-response relationship. With the collection of more data Muralidharan and Prakash were able to ask whether the program was more effective for the students who were neither so close nor so far from the school that a bicycle wouldn’t make a difference. Indeed, the program was most effective for students who lived at bicycle-relevant distances.

These videos are an interesting peek at some of the questions economists ask and the methods they use to answer those questions. The videos would be excellent for classroom use–challenge your students after the first video to come up with potential problems with the triple difference method and see if they can identify another research design that would address these problems!

Addendum: Here are previous MR posts on Karthik Muralidharan’s important research program.


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