GIVEN the long history of making racial slurs about the efforts of some workers, any study casting black and Hispanic men as lazier than whites and Asians is sure to court controversy. A provocative new working paper by economists Daniel Hamermesh, Katie Genadek and Michael Burda sticks a tentative toe into these murky waters. They suggest that America’s well-documented racial wage gap is overstated by 10% because minorities, especially men, spend larger portions of their workdays not actually working. After rejecting a number of plausible explanations for why this might be, the authors finally attribute the discrepancy to unexplained “cultural differences”.

Acutely aware of the sensitivity of these findings, the professors delayed publication until after the presidential election. “I knew full well that Trump and his minions would use it as a propaganda piece,” says Mr Hamermesh, a colourful and respected labour economist. The paper may yet be seized on by those who are keen to root out “political correctness” and are perennially unhappy with current anti-discrimination laws.