Actions often end up being dictated not by what is known to be true but by what people believe to be true.

From Ideas that spread fast and slow by Andrew Gelman. Read his post for his discussion, but I liked this example.

What I focus on with this story is the dual issues of Knowledge and Incentives and how the real world rarely works as intended. Specifically, in this case, Columbia knew what the right solution should be but for reasons unclear, took a different approach (Knowledge issue). And then compounded the Knowledge issue by creating incentives for its tenants to choose the less effective approach. All within the world and control of Columbia University.

The example I have in mind is roach extermination. When I worked with Ginger Chew and her colleagues in the school of public health at Columbia several years ago, I learned that the way to get rid of roaches in your apartment is to clean up your apartment, throw away all the open food, put boric acid in the cracks in your floor and walls, and seal up the cracks. It’s not easy but it does the job. But that’s not what they do in the Columbia-owned-and-operated building where I live. What they do is, every month they put a signup sheet up by the elevator and then an exterminator comes into the building and bombs the apartments of everyone on the list. The same people sign up every month, of course. Instead of thinking, “Hey, bombing doesn’t work,” they seem to think that it’s something they need to do monthly. Good business for the exterminators but not so effective at getting rid of roaches.

So why do they do it that way? One thing I’m definitely not going to do is talk with my neighbors and suggest they try a different approach. My impression is that people get very defensive about things like this. Also, I’m no roach expert; really I’d want to bring someone in from the school of public health to have this conversation.

Anyway, my impression is that people like any treatment that feels like “pushing a button” and they don’t like anything that feels like work. And if you tell people that pushing the button doesn’t really work, they get all bristly on you. Even though, in this case I think the effective treatment is ultimately less work than the bomb. Unfortunately, Columbia has it set up so they bomb for free, but they don’t provide a free cleanup and sealing service.

And Gelman's right about the bristly part as well. Actions often end up being dictated not by what is known to be true but by what people believe to be true.