Economists have shown that large and persistent differences in productivity levels across businesses are ubiquitous. This finding has shaped research agendas in a number of fields, including (but not limited to) macroeconomics, industrial organization, labor, and trade. This paper surveys and...

In markets where spatial competition is important, many models predict that average prices are lower in denser markets (i.e., those with more producers per unit area). Homogeneous-producer models attribute this effect solely to lower optimal markups. However, when producers instead differ in...

Many studies have documented large and persistent productivity differences across producers, even within narrowly defined industries. This paper both extends and departs from the past literature, which focused on technological explanations for these differences, by proposing that demand-side...