The answer to the question in the title is: A lot. In this essay, I argue that the history of macroeconomics during the 20th century can be divided in three epochs: Pre 1940. A period of exploration, where macroeconomics was not macroeconomics yet, but monetary theory on one side, business cycle...

European unemployment is widely regarded as a problem of excessive real wages. This view as it is usually expressed carries the disturbing implication that there is a sharp conflict between the interests of those currently employed and the unemployed because it suggests that increases in...

We interpret fluctuations in GNP and unemployment as due to two types of disturbances: disturbances that have a permanent effect on output and disturbances that do not. We interpret the first as supply disturbances, the second as demand disturbances. We find that demand disturbances have a hump...

This paper investigates the relation between growth forecast errors and planned fiscal consolidation during the crisis. We find that, in advanced economies, stronger planned fiscal consolidation has been associated with lower growth than expected, with the relation being particularly strong,...

We present a picture of the labor market, one with large flows of jobs and workers, and matching. We develop a consistent approach to the interaction among those flows and the stocks of unemployed workers and vacant jobs, and to the determination of wages. We estimate the matching function,...

Current account imbalances have steadily increased in rich countries over the last 20 years. While the U.S. current account deficit dominates the numbers and the news, other countries, especially within the Euro area, are also running large deficits. These deficits are different from the Latin...

In China, local governments have actively contributed to the growth of new firms. In Russia, local governments have typically stood in the way, be it through taxation, regulation, or corruption. There appears to be two main reasons behind the behavior of local governments in Russia. First,...

Firms often receive multiple acceptable applications for vacancies, requiring a choice among candidates. This paper contrasts equilibria when firms select workers at random and when firms select the worker with the shortest spell of unemployment, called ranking. With the filling of vacancies...

European unemployment has been steadily increasing for the last 15 years and is expected to remain very high for many years to come. In this paper, we argue that this fact implies that shocks have much more persistent effects on unemployment than standard theories can possibly explain. We...

This paper shows how one can interpret the joint movements of wages, unemployment and vacancies in the Phillips and Beveridge spaces to learn about the origins of the movements in unemployment. The view of the labor market underlying the conceptual framework emphasizes flows, matching, and Nash...