We develop a model of production and exchange with uncertainty concerning the quality of commodities and study the role of fiat money in ameliorating frictions caused by private information. The model is specified so that, without private information, only high-quality commodities are produced, and there is no welfare gain from using money. With private information, there can be equilibria (and sometimes multiple equilibria) where low-quality commodities are produced, and money can increase welfare. Money works by promoting useful production and exchange. In efficient monetary equilibria, agents adopt strategies that increase the probability of acquiring high-quality output.

The essential function of money is its role as a medium of exchange. We formalize this idea using a search-theoretic equilibrium model of the exchange process that captures the "double coincidence of wants problem" with pure barter. One advantage of the framework described here is that it is very tractable. We also show that the model can be used to address some substantive issues in monetary economics, including the potential welfare-enhancing role of money, the interaction between specialization and monetary exchange, and the possibility of equilibria with multiple fiat currencies.

We document and attempt to explain the observation that automobile insurance premiums vary dramatically across cities. We argue that high premiums can be attributed, at least in part, to large numbers of uninsured motorists in some markets, while uninsured motorists can be attributed to high premiums. We construct a simple noncooperative equilibrium model that can generate inefficient equilibria with uninsured drivers and high, yet actuarially fair, premiums. For certain parameterizations, an efficient full-insurance equilibrium and inefficient high-price equilibria with uninsured drivers exist simultaneously, helping to explain price variability across otherwise similar cities. Policy implications are discussed.

The essential function of money is its role as a medium of exchange. The authors formalize this idea using a search-theoretic equilibrium model of the exchange process that captures the "double coincidence of wants problem" with pure barter. One advantage of the framework described here is that it is very tractable. The authors also show that the model can be used to addre ss some substantive issues in monetary economics, including the potenti al welfare-enhancing role of money, the interaction between specializat ion and monetary exchange, and the possibility of equilibria with multip le fiat currencies.

We study the long-run relation between money (inflation or interest rates) and unemployment. We document positive relationships between these variables at low frequencies. We develop a framework where money and unemployment are modeled using explicit microfoundations, providing a unified theory to analyze labor and goods markets. We calibrate the model and ask how monetary factors account for labor market behavior. We can account for a sizable fraction of the increase in unemployment rates during the 1970s. We show how it matters whether one uses monetary theory based on the search-and-bargaining approach or on an ad hoc cash-in-advance constraint.

We develop a general equilibrium model where entrepreneurs finance random investment opportunities using trade credit, bank-issued assets, or currency. They search for bank funding in over-the-counter markets where loan sizes, interest rates, and down payments are negotiated bilaterally. The theory generates pass-through from nominal interest rates to real lending rates depending on market microstructure, policy, and firm characteristics. Higher banks' bargaining power, for example, raises pass-through but weakens transmission to investment. Interest rate spreads arise from liquidity, regulatory, and intermediation premia and depend on policy described as money growth or open market operations.

There is much discussion of the relationships between crime, inequality, and unemployment. We construct a model where all three are endogenous. We find that introducing crime into otherwise standard models of labor markets has several interesting implications. For example, it can lead to wage inequality among homogeneous workers. Also, it can generate multiple equilibria in natural but previously unexplored ways; hence two identical neighborhoods can end up with different levels of crime, inequality, and unemployment. We discuss the effects of anti-crime policies like changing jail sentences, as well as more traditional labor market policies like changing unemployment insurance.(This abstract was borrowed from another version of this item.)

In Corbae, Temzelides, and Wright (2001) (hereafter, CTW) we proposed a new version of the framework that uses bilateral matching to model the exchange process, and in particular to model the use of money as a medium of exchange. Our version does not have agents meeting exogenously and at random, but rather has agents meeting endogenously. That is, agents are matched at each date subject to a stability condition that requires, roughly, that no agents prefer to be paired with each other or to be unmatched, rather than to be paired with the partners they get along the equilibrium path. While similar in spirit to the cooperative matching concept introduced by David Gale and Lloyd Shapley (1962), we had to generalize their framework to dynamic models because we are interested in monetary economics. Here we present a version of the solution concept in CTW, specialized in some ways but also generalized to include extrinsic uncertainty (sunspots). We then discuss some applications of endogenous matching models to issues that have previously been addressed using random matching, including the existence of sunspot equilibria and the efficiency of inside versus outside money. One of our main goals is to show how endogenous matching is a useful alternative to random matching. This may be interesting to those who think that bilateral trade is a reasonable friction upon which to build a theoretical foundation for monetary economics but perhaps think that random matching is an extreme and unrealistic simplification. Another goal is to provide examples where it makes a difference for substantive results how we model the matching process, and also examples where it does not. I. Endogenous Matching