The last decade has not been good for many advanced economies. The Global Financial Crisis, a second recession in the Euro area and central banks hitting the zero lower bound have led to disappointing GDP growth rates. But GDP growth rates can be a misleading indicator about the true performance of different economies. For example, as Matt O'Brien summarizes well , Japan has done much better than what most people believe. The confusion comes from the fact that there are two forces driving GDP growth. One is the number of hours we work and the other one is how productive those hours are. The absolute number of hours we work is a function of the population of a country. Because of that reason we usually measure GDP per capita growth instead of GDP growth. But this is not enough. Hours per capita can change in response to two forces. First, age matters. Typically engagement in the labor market declines with age, an aging country is likely to have fewer hours per capita. Second, the l...