Intertemporal Insurance

This paper develops a discrete-time general equilibrium model of insurance using standard techniques of intertemporal finance. The underlying source of uncertainty is modeled as a marked point process. The paper begins by characterizing Walrasian equilibrium on the event tree generated by the accident process. The corresponding Arrow-Debreu-Radner contingent-commodity prices allow the pricing of insurance contracts. A transformation of the underlying probability measure gives an alternative characterization of insurance contract prices plus accumulated payouts as martingales. A direct application of the usual dynamic spanning argument demonstrates that one insurance contract for each type of accident suffices, at least generically, to achieve market completeness. The theory is illustrated by a simple example in which consumers have Cobb-Douglas preferences and experience accidents at a rate which varies across individuals but remains constant over time, the traditional setting for much of insurance theory. This paper was presented at the Financial Institutions Center's May 1996 conference on "

The Dynamics of Retail Oligopolies

Dynamic Models, Retail Indusry, Markov perfect equilibrium, Oligopoly

Clubs and the Market

This paper defines a general eqilibrium model with exchange and club formation. Agents trade multiple private goods widely in the market, can belong to several clubs, and care about the characteristics of the other members of their clubs. The space of agents is a continuum, but clubs are finite. It is shown that (i) competitive equilibria exist, and (ii) the core coincides with the set of equilibrium states. The central subtlety is in modeling club memberships and expressing the notion that membership choices are consistent across the population.clubs; continuum models; public goods; core; club equilibrium

Patient Welfare and Patient Compliance: An Empirical Framework for Measuring the Benefits from Pharmaceutical Innovation

The main goal of this paper is to develop an empirical framework for evaluating the patient welfare benefits arising from pharmaceutical innovation. Extending previous studies of the welfare benefits from innovation (Trajtenberg, 1990; Hausman, 1996), this paper unpacks the separate choices made by physicians and patients in pharmaceutical decisionmaking and develops an estimable econometric model which reflects these choices. Our proposed estimator for patient welfare depends on (a) whether patients comply with the prescriptions they receive from physicians and (b) the motives of physicians in their prescription behavior. By focusing on compliance behavior, the proposed welfare measure reflects a specific economic choice made by patients. We review evidence that the rate of noncompliance ranges up to 70%, suggesting an important gulf between physician prescription behavior and realized patient welfare. Since physicians act as imperfect but interested agents for their patients, the welfare analysis based on compliance must account for the nonrandom selection of patients into drugs by their physicians. The key contribution of this paper resides in integrating the choices made by both physicians and patients into a unified theoretical framework and suggesting how the parameters of such a model can be estimated from data.

The Inevitable Trend Toward Universally Recognizable Signals of Property Claims: An Essay for Carol Rose

Presented at the 2010 Brigham-Kanner Property Rights Conference

A Theory of Firm Formation and Skills Acquisition

We present a theory of production that begins with an exogenously specified set of technologies, accessible to each potential firm. The technologies used in equilibrium are endogenous. Labor skills are differentiated, and the labor skills are acquired endogenously by workers, possibly by bearing private costs, and possibly by attending school. A technology can be used by a group of agents having the appropriate skills. We allow that workers care about the production plans in their firms, and will accept lower compensation to satisfy their preferences on production plans. In a continuum model, we show what price systems are required so that competitive equilibrium exists and core outcomes are equivalent to competitive outcomes.

Migration with local public goods and the gains from changing places

Without public goods and under fairly standard assumptions, in Hammond and Sempere (J Pub Econ Theory, 8: 145–170, 2006) we show that freeing migration enhances the potential Pareto gains from free trade. Here, we present a generalization allowing local public goods subject to congestion. Unlike the standard literature on fiscal externalities, our result relies on fixing both local public goods and congestion levels at their status quo values. This allows constrained efficient and potentially Pareto improving population exchanges regulated only through appropriate residence charges, which can be regarded as Pigouvian congestion taxes

Clubs and the Market: Large Finite Economies

We study large finite club economies in which agents can belong to several clubs, and care about the characteristics of the other club members. Club memberships must be integer consistent in aggregate. We show that states in the approximate core can approximately be decentralized by prices for private goods and for club memberships, that the approximate core is nonempty, and that approximate club equilibria exist. Our arguments use the convexification tools used for private goods economies, but we also develop a new tool to address the consistency requirement on memberships that are special to club economies. This tool allows us to overcome the integer consistency problems that are avoided in our (1999) paper by assuming a continuum of agents.clubs; e-cores; approximate equilibrium; decentralization

Supermarket Promotions and Food Prices: A Note

Using a sample comprising nearly 250,000 weekly prices from the largest seven UK supermarket chains, this note investigates two pricing practices that have attracted public interest: the tendency for promotions to 'disguise' rises in non-sale prices and the inflation of prices prior to sales which 'exaggerate' the discount. Analysing price dynamics before and after periods of promotional discounting results show post-sale prices are typically lower than pre-sale prices, contrary to the disguise hypothesis. We do, however, find evidence of exaggeration of the discount, which may potentially explain why prices fall after discounts, although the evidence is not sufficiently widespread for this to be the sole cause. Results parallel the competition authority's view of supermarket promotions and point to the useful contribution that retail price microdata might play in keeping prices in check in countries where highly concentrated retail sectors raise similar concerns

Survey Evidence on Conditional Norm Enforcement

We discuss survey evidence on individuals' willingness to sanction norm violations - such as evading taxes, drunk driving, fare dodging, or skiving o work - by expressing disapproval or social exclusion. Our data suggest that people condition their sanctioning behavior on their belief about the frequency of norm violations. The more commonly a norm violation is believed to occur, the lower the individuals' inclination to punish it. Based on an instrumental variable approach, we demonstrate that this pattern reflects a causal relationship