What we know and do not know about the natural rate of unemployment

Over the past three decades, much research has attempted to identify the determinants of the natural rate of unemployment. The authors reach two main conclusions about this body of work. First, there has been considerable theoretical progress over the past thirty years. A framework emerged that can be used to think, for example, about the relation between technological progress and unemployment. Second, empirical knowledge lags behind. Economists don't have a good quantitative understanding of the determinants of the natural rate, either across time or countries. The authors look at two issues, the relation of wages to unemployment and the rise of European unemployment.