My research has focused broadly on understanding differences in economic performance. This includes work on:

Understanding income differences – how to measure cross-country income differences and the role of differences in the availability of human and physical capital and differences in productivity, see the Penn World Table and the associated paper on the Next Generation of the Penn World Table (American Economic Review, 105(10)). My recent work shows that international income differences have been overestimated in recent years.

Understanding economic growth – what can explain growth differences across (advanced) economies. Why did productivity growth accelerate in the US but slow down in Europe? And here too, how sure can we be of observed growth differences? Here I have tried to improve how we measure the role of banks in the economy and how to interpret short-run movements in productivity.