My Favorite Example of a Biased Statistic
By Arnold Kling
In a column pointing to research findings on a variety of topics, William Saletan includes
The richer the country, the lower the ratio of male-to-female promiscuity.
In no country is the ratio of male-to-female promiscuity measured in an unbiased manner. The true ratio of male-to-female promiscuity is determined entirely by the ratio of females to males, which means that it is probably close to one. If your survey says otherwise, then your survey responses are biased. In Learning Economics, this essay is reprinted as “The Omniscient Voyeur.”
Nearly-omniscient Tyler Cowen provided the unbiased pointer.