The fear that automation in the form of robots or artificial intelligence is going to destroy jobs is widespread. But it can be difficult to gauge just how serious to take the threat. Different reports offer different estimations of how many jobs will be lost, while politicians and economists argue that technology creates as many jobs as it destroys, maintaining an equilibrium in employment over the long run.

But is this really true? A new study from the National Bureau of Economic Research aims to add some solid numbers to the debate, looking at the historical effects of robots on employment in the US. Economists Daron Acemoglu and Pascual Restrepo studied the US labor market between 1990 and 2007, looking at employment rates in different areas and industries while controlling for the influence of factors like increased imports from China and the offshoring of jobs.