This paper reviews the empirical evidence on firm heterogeneity in international trade. A first wave of empirical findings from micro data on plants and firms proposed challenges for existing models of international trade and inspired the development of new theories emphasizing firm...

We identify three separate stages in the post-World War II history of applied microeconomic research: A generally non-mathematical period; a period of consensus (from the 1960s through the early 1990s) characterized by the use of mathematical models, optimization and equilibrium to generate and...

New data-gathering techniques, often referred to as "Big Data" have the potential to improve statistics and empirical research in economics. In this paper we describe our work with online data at the Billion Prices Project at MIT and discuss key lessons for both inflation measurement and some...