Signalling helps explain what happened when Washington and those other states stopped firms from obtaining job-applicants’ credit scores. Credit history is a credible signal: it is hard to fake, and, presumably, those with good credit scores are more likely to make good employees than those who default on their debts. Messrs Clifford and Shoag found that when firms could no longer access credit scores, they put more weight on other signals, like education and experience. Because these are rarer among disadvantaged groups, it became harder, not easier, for them to convince employers of their worth.