The Data Detective: Ten Easy Rules to Make Sense of Statistics

by Tim Harford

About a decade ago, researchers led by Yale University’s Dan Kahan showed students some footage of a protest outside an unidentified building. Some of the students were told that it was a pro-life demonstration outside an abortion clinic. Others were informed that it was a gay rights demonstration outside an army recruitment office. The students were asked some factual questions. Was it a peaceful protest? Did the protesters try to intimidate people passing by? Did they scream or shout? Did they block the entrance to the building? The answers people gave depended on the political identities they embraced. Conservative students who believed they were looking at a demonstration against abortion saw no problems with the protest: no abuse, no violence, no obstruction. Students on the left who thought they were looking at a gay rights protest reached the same conclusion: the protesters had conducted themselves with dignity and restraint. But right-wing students who thought they were looking at a gay rights demonstration reached a very different conclusion, as did left-wing students who believed they were watching an anti-abortion protest. Both these groups concluded that the protesters had been aggressive, intimidating, and obstructive.3