hISTORY IS OVER:

MIT economist Daron Acemoglu and James Robinson of Harvard, famous for the idea that "inclusive institutions" are the key to national development, teamed up with Suresh Naidu and Pascual Restrepo to tackle the problem. They use a large number of different statistical techniques to examine the effect of democratizations. They also use an alternate technique, where they look at waves of democratization.

All of the methods give the same answer: Democracy increases gross domestic product  by about 20 percent in the long run.

Follow @brothersjudd