F OR APARTMENT-HUNTERS in Santa Ana, California, a city about an hour south of Los Angeles, a $625-per-month sublet recently listed on Craigslist, a classified-advertising website, might seem ideal. The apartment, which is shared among four 20- and 30-somethings, is spacious, tidy and only minutes from a park. It comes with conditions, however: “No racists, no homophobes, no Trump supporters!” Discrimination of this sort is not uncommon on Craigslist, which is based in San Francisco. Toni, an artist seeking a flatmate in Ann Arbor, Michigan, advises potential applicants, “I won’t live with anyone bigoted, racist, sexist, or Trump supporting.” Another Craigslist-poster in Missoula, Montana warns, “Trump supporters need not apply”.

One might assume that such political preferences would be held only among staunch partisans. But a new paper by Richard Shafranek, a political science P h D student at Northwestern University, suggests they are relatively common. In his study, published last month in the journal Political Behaviour, Mr Shafranek surveyed a group of students at a large midwestern university. He asked them to answer a series of demographic questions followed by questions about their politics, interests and personal habits. Subjects in the study were then presented with two fictitious flatmates and asked to rate each on a scale of one to seven based on the same set of demographic and personal characteristics. This was repeated for ten hypothetical housemate pairs.