Shouyong Shi

Pricing and Matching with Frictions

Suppose that n buyers each want one unit and m sellers each have one or more units of a good. Sellers post prices, and then buyers choose sellers. In symmetric equilibrium, similar sellers all post one price, and buyers randomize. Hence, more or fewer buyers may arrive than a seller can accommodate. We call this frictions. We solve for prices and the endogenous matching function for finite n and m and consider the limit as n and m grow. The matching function displays decreasing returns but converges to constant returns. We argue that the standard matching function in the literature is misspecified and discuss implications for the Beveridge curve.

A Divisible Search Model of Fiat Money

This paper extends the Kiyotaki-Wright search model of fiat money to allow for divisible money and goods. The extension allows me to examine the standard issues in monetary economics, such as the neutrality and super-neutrality of money, by severing the artificial link in the Kiyotaki-Wright model between the money supply and the number of money holders. It is shown that money is neutral, but not super-neutral. Money growth generates a trading opportunity effect: it changes the fraction of different agents in the economy and hence changes the probability with which agents have a successful match. In addition, money growth has a negative effect on the real money balance that is familiar in Walrasian monetary models. The balance of the two effects can imply a positive optimal money growth rate.

A directed search model of inequality with heterogeneous skills and skill-biased technology

In this paper I analyse the directed search/matching problem in an economy with heterogeneous skills and skill-biased technology. A unique symmetric equilibrium exists and is socially efficient. Matching is partially mixed in the equilibrium. A high-tech firm receives both skilled and unskilled applicants with positive probability, and favours skilled workers, while a low-tech firm receives only unskilled applicants. The model generates wage inequality among identical unskilled workers, as well as between-skill inequality, despite the fact that all unskilled workers perform the same task and have the same productivity in the two types of firms. Inequality has interesting responses to skill-biased technological progress, a general productivity slowdown, and an exogenous increase in the skill supply elasticity.

Frictional Assignment. I. Efficiency

Abstract This paper examines the two-sided matching problem where the agents on each side of the market are heterogeneous and the matching process is time consuming. This is cast in a labor market setting where workers of different skills match with different machine qualities. I characterize the efficient allocation and then show that it can be decentralized by a market mechanism. The efficient assignment is not always positively assortative, despite the fact that machine qualities and skills are complementary in production. To decentralize the efficient allocation, the market mechanism requires the firms to post wages and commit each machine quality to a particular skill. Implications on wage inequality are briefly examined. Journal of Economic Literature Classification Numbers: J31, E24, J64.

Friedman Meets Hosios: Efficiency in Search Models of Money

This article studies optimal monetary policy in an economy with endogenous search decisions. We show that the same frictions that give fiat money a positive value generate an inefficient quantity of goods in each trade and an inefficient number of trades. The Friedman rule eliminates the first inefficiency and the Hosios rule the second. A monetary equilibrium attains the social optimum if and only if both rules are satisfied. When they cannot be satisfied simultaneously, optimal monetary policy achieves only the second best. We analyse the conditions under which the second-best monetary policy exceeds the Friedman rule.

Credit and Money in a Search Model with Divisible Commodities

This paper examines the competition between money and credit in a search model with divisible commodities. It is shown that fiat money can be valuable even though it yields a lower rate of return than the coexisting credit. The competition between money and credit increases efficiency. The monetary equilibrium with credit Pareto dominates the monetary equilibrium without credit whenever the two coexist. When a credit is repaid with money, the competition also bounds the purchasing power of money from below by that of credit and so eliminates the weak inefficient monetary equilibrium found in previous search models. With numerical examples, three different monetary equilibria are ranked and the properties of the interest rate are examined.

Habits and Time Preference

This paper proposes a utility function incorporating both habit formation and an endogenous rate of time preference in a manner consistent with the intuition of Irving Fisher regarding the influence of past consumption on impatience. It is shown that the ne w specification is tractable and generates new predictions in the cont ext of three model economies: (1) a closed economy with heterogeneous agents, (2) a small open economy with one traded good and one nontra ded good, and (3) a small open economy with a traded good and domestic money. Copyright 1993 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.

Labor market search and the dynamic effects of taxes and subsidies

Abstract This paper integrates the search model of unemployment into an intertemporal framework and examines the dynamic effects of a labor income tax, a capital income tax, an unemployment subsidy, a vacancy subsidy, and an investment tax credit. We also compute the marginal deadweight losses associated with these policies. The presence of unemployment reduces the relative welfare cost of capital income taxation to labor income taxation. With realistic parameter values, labor income taxation can even be more costly than capital income taxation. A vacancy subsidy is efficient, self-financed and shares many features with an investment tax credit. An unemployment subsidy is very inefficient. Alternative matching and wage determination schemes are analyzed.

Viewpoint: A microfoundation of monetary economics

In this lecture, I explain what the microfoundations of money are about and why they are necessary for monetary economics. Then, I review recent developments of a particular microfoundation of money, commonly known as the search theory of money. Finally, I outline some unresolved issues.

Efficient Search on the Job and the Business Cycle, Second Version

We build a directed search model of the labor market in which workers’ transitions between unemployment, employment, and across employers are endogenous. We prove the existence, uniqueness and efficiency of a recursive equilibrium with the property that the distribution of workers across employment states affects neither the agents’ values and strategies nor the market tightness. Because of this property, we are able to compute the equilibrium outside the non-stochastic steady-state. We use a calibrated version of the model to measure the effect of productivity shocks on the US labor market. We find that productivity shocks generate procyclical fluctuations in the rate at which unemployed workers become employed and countercyclical fluctuations in the rate at which employed workers become unemployed. Moreover, we find that productivity shocks generate large counter-cyclical fluctuations in the number of vacancies opened for unemployed workers and even larger procyclical fluctuations in the number of vacancies created for employed workers. Overall, productivity shocks alone can account for 80 percent of unemployment volatility, 30 percent of vacancy volatility and for the nearly perfect negative correlation between unemployment and vacancies.