Nobel economics prize goes to 'natural experiments' pioneers

Unlike in medicine or other sciences, economists cannot conduct rigidly controlled clinical trials. Instead, natural experiments use real-life situations to study impacts on the world, an approach that has spread to other social sciences.

Past Nobel Economics prizes have been dominated by U.S. institutions and this was no exception.

Canada-born Card currently works at the University of California, Berkeley; Angrist at Massachusetts Institute of Technology; and Dutch-born Imbens at Stanford University.

One experiment by Card on the impact on the fast-food sector of a minimum wage increase in the U.S. state of New Jersey in the early 1990s prompted a review of the conventional wisdom that such increases should always lead to falls in employment.