We validate experimentally a new survey item to measure the preference for competition. The item, which measures participants' agreement with the statement "Competition brings the best out of me", predicts individuals' willingness to compete in the laboratory after controlling for their ability,...

We study the effects of a voluntary skill certification scheme in an online freelancing labour market. We show that obtaining skill certificates increases freelancers' earnings. This effect is not driven by increased freelancer productivity but by decreased employer uncertainty. The increase in...