People say they want their politicians to be honest but usually find it hard to tell if that is what they are getting. However, two economists realized that even when it‘s difficult to assess an individual’s honesty, statistical tests can measure the proportion of truth-telling and find characteristics associated with greater honesty. In particular, they found that Spaniards seeking an honest mayor should look outside the major parties.

Universitat Pompeu Fabra PhD student Katharina Janezic and Dr Aina Gallego of the Institut Barcelona Estudis Internationals sent surveys to 816 Spanish mayors and asked them how interested they were in receiving the study’s results. Almost half said they were very keen and most of the rest were “quite interested”. At the end of the survey, the mayors were asked to flip a coin and report the results. Only those who answered heads would get the information they desired.

There was no way of knowing whether an individual mayor told the truth, but the sample was large enough the true result overall could not have been very different from 50 percent. Yet 68 percent reported their coin toss yielded heads, a near impossibility if all were reporting honestly, Janezic and Gallego report in Proceedings of the National Academy of Sciences, indicating approximately 36 percent who flipped tails lied.

The fact more than half told the truth, even without the risk of getting caught, may surprise some people accustomed to the view that “all politicians lie”, undercutting the cynicism that benefits the actual liars.

When the team compared subgroups, men and women were almost exactly as likely to report a head toss, but political affiliation mattered. Of the more than half the mayors who came from one of Spain’s two major parties (the center-right Partido Popular and center-left Partido Socialista Obrero Español), 71 percent reported heads compared to 64 percent of independents and members of smaller parties.

“Together with the finding that all groups had significant levels of lying, this suggests that members of major parties lied significantly more,” the paper notes. The sample size was insufficient for greater detail.

Unsurprisingly, those most anxious to get the results were also more likely to lie – 76 percent of the “very interested” respondents reported a head.

Studies of honesty in other groups have usually tested whether monetary rewards induce dishonest behavior. However, the authors avoided this based on past research that politicians are deeply wary of financial inducements. Information, on the other hand, could not be considered an illegal bribe but was sufficiently valuable to most participants to test the strength of their commitment to the truth. Interestingly, the comparable studies the authors could find reported greater honesty among the general population and bankers when money was on offer than from Spain’s mayors with the desired information.

However, in elections held shortly after the study, mayors who reported heads were more likely to win than those who answered honestly against their interest.