How to Build a Sidewalk

If you had to build a sidewalk into a school or work, how would you do it? One way is to take a survey and ask people questions like, “If there was a sidewalk here, would you use it?” Another way to find out how to build a sidewalk is to ask their opinion. For example, “Where is the best place to build a sidewalk?” Both ways of gathering data to build a sidewalk are a poor paradigm since the incentives are misaligned. In the first case, respondents might lie especially if they did not have to share in the cost of building the sidewalk. In the second case, respondents will answer in a way that maximizes their benefit and minimizes their cost. In the second case there’s also a game being played. The game goes something like, “If Juan wants a sidewalk there, I’ll say I don’t like that sidewalk just so Juan does not feel empowered by his decision.”

The right way to build a sidewalk is to not build the sidewalk at all. People will choose a path to the front door that minimizes their cost and maximizes their benefit. The paths that have worn out the grass or packed down the snow are the most popular paths. Choose to build the sidewalk on those paths since the paths don’t lie and appear to be the most efficient entrance to the building for the most people.

The way to build a sidewalk is to look at what people do and not what they say. The same approach could be used to determine the best schedule.