20 February 2013

Omitted Variable Bias: Slovenly Men Edition

Free exchange
STEPHEN DUBNER publishes a reader question:
I live with four guys in a house. We had no cleaning schedule until about a month ago, but the house was never cluttered, and was more than clean enough for actual women to feel comfortable visiting. Even the bathroom was clean enough for the girls to freely use it without vomiting. However since we have implemented our cleaning schedule the house has gotten into worse and worse shape. The toilet downstairs is even looking so bad I don't want to use it. What gives?
Mr Dubner comments:
Okay, everybody, let's hear what you have to say about private vs. public incentives, moral hazard, and the general cleanliness of men.
Incentives, right!? Beware unintended consequences! Only, I suspect omitted variable bias. If the house was previously neat and clean, why did the roommates feel the need to adopt a cleaning schedule? I suspect that an unobserved factor led the roommates to introduce a schedule and contributed to a deterioration in the neatness of the house. Perhaps one of the roommates, a neat freak, began a serious relationship and started spending lots of of time away from the house. Or perhaps he simply grew tired of doing all the cleaning and resolved to let the others do their share or live in filth. Or he sustained an injury. One must always be wary of spurious correlation!