Although economists have long been interested in the implications of Marshallian externalities (i.e., industry-level external economies of scale) for trading economies, the large number of equilibria that they typically imply has kept such externalities out of the recent quantitative trade...

Increasing returns are as fundamental a cause of international trade as comparative advantage, but their role has until recently been neglected because of the problem of modelling market structure. Recently substantial theoretical progress has been made using three different approaches. These...

There are two principal theories of why countries or regions trade: comparative advantage and increasing returns to scale. Yet there is virtually no empirical work that assesses the relative importance of these two theories in accounting for production structure and trade. We use a framework...

A positive correlation between insurance coverage and ex post risk can be an indicator for private information in insurance markets. However, this test fails if agents have heterogeneous risk attitudes. We propose a new test that conditions on unobserved types of individuals who differ in their...

We present a graphical framework for analyzing both theoretical and empirical work on selection in insurance markets. We begin by using this framework to review the "textbook" adverse selection environment and its implications for insurance allocation, social welfare, and public policy. We then...

We describe recent advances in the empirical analysis of insurance markets. This new research proposes ways to estimate individual demand for insurance and the relationship between prices and insurer costs in the presence of adverse and advantageous selection. We discuss how these models permit...

This paper derives a portfolio diversification rationale for a trade policy regime that insures returns to nondiversifiable human capital investment. In the absence of complete insurance markets for human capital, the decentralized equilibrium is characterized by excessive specialization. The...

A large empirical literature found that the correlation between insurance purchase and ex post realization of risk is often statistically insignificant or negative. This is inconsistent with the predictions from the classic models of insurance a la Akerlof (1970), Pauly (1974) and Rothschild and...

Standard policies to correct market power and selection can be misguided when these two forces co-exist. Using a calibrated model of employer-sponsored health insurance, we show that the risk adjustment commonly used by employers to offset adverse selection often reduces the amount of...

The willingness to pay for insurance captures the value of insurance against only the risk that remains when choices are observed. This paper develops tools to measure the ex-ante expected utility impact of insurance subsidies and mandates when choices are observed after some insurable...