The Joy of Forced Experimentation

In February 2014, portions of the London Underground shut down for three days as employees went on strike over plans to close ticket offices and eliminate 1,000 jobs. For commuters, the shutdown caused widespread misery. For economists, it sparked joy.

A Striking Finding

The partial Tube shutdown created a natural experiment, making economists giddy. With certain stations and train lines shuttered, some commuters were forced to find a new way into the office while others weren’t affected.

Economists Shaun Larcom, Ferdinand Rauch and Tim Willems analyzed individual’s travel data on the London Underground from January 19, 2014 to February 15, 2014 to suss out the impact of the transit strike. Their findings are, well, striking.

Before the strike, about 90% of riders got on and off the Tube at the same stations every day. The transit strike, demarcated by the vertical lines in the figure below, forced behavior change as some stations closed. During this time, roughly 30% of commuters altered their entry point. A similar percentage changed their exit point.

Source: Shaun Larcom, Ferdinand Rauch, and Tim Willems, The benefits of forced experimentation: Striking evidence from the London underground network, September 15, 2015. Annotations by Below the Line.

Larcom, Rauch and Willems found that:

The strike brought about some lasting changes in behavior, as the fraction of commuters that made use of their modal station seemingly drops after the strike.