difference-in-differences

When a major bridge connected millions of people in northwest Bangladesh to the capital in 1998, did the region's economy take off? This beginner-friendly Python tutorial uses satellite images of nighttime lights to compare the connected region with a similar one that stayed isolated, before and after the bridge opened.

Can we still find the true effect of a job training program on earnings if we compare trainees with ordinary survey respondents instead of a randomized control group? This Python tutorial shows that adding background characteristics fixes the estimate only when they adjust the expected earnings trend of the comparison group. It comes with an interactive app that runs in your web browser.

Do gender quotas raise the share of women in national parliaments? In Stata, we compare 9 countries that adopted quotas in different years with look-alike groups built from 110 countries without quotas, and find an average gain of about 8 percentage points that varies a lot across countries. The tutorial includes an interactive app that runs in your web browser.

Did the 1988 tobacco tax in California reduce smoking? In Stata, we compare three ways of building a comparison for California from other states, including a newer method that blends their strengths, and all three agree that cigarette sales fell, though by different amounts. It comes with an interactive app that runs in your web browser.

What happens to nearby home prices when a registered sex offender moves into a neighborhood? We compare homes close to the address with homes a little farther away, before and after the move, and show how the distance chosen as the cutoff can change the answer. This R tutorial comes with an interactive app that runs in your web browser.

Did expanding Medicaid health coverage to low-income adults reduce deaths? We compare counties in states that expanded coverage with counties in states that did not, and show how counting each county equally or each person equally can change the answer. This R tutorial includes an interactive app that runs in your web browser.