Natural experiment

Unlike scientists in a laboratory, economists do not, as a rule, carry out controlled experiments on real economies (see, however, randomised control trials). But sometimes circumstances throw up similar opportunities, known as natural experiments—eg, a rise in the minimum wage in one place but not another. The pioneering work in this field was carried out by David Card, who shared the Nobel prize in 2021 (see article) and the late Alan Krueger (see this appreciation).