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Abstract:
There has been much discussion of the relationships between crime, inequality and unemployment. We construct a model where all three are endogenous. Introducing crime into otherwise standard models affects the labor market in several interesting ways. For example, we show how the crime rate affects the
unemployment rate and vice-versa; how the possibility of criminal activity can lead to wage inequality among homogeneous workers; and how the possibility of crime can generate multiple equilibria in natural but previously unexplored ways. In particular, two fundamentally identical neighborhoods may easily end up with different levels of unemployment, inequality, and crime. The model can be used to study the equilibrium effects of anti-crime policies, such as changes in apprehension rates or jail sentences, as well as more traditional labor market
policies such as unemployment insurance.

Abstract:
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.

Abstract:
Search-theoretic models of monetary exchange are based on explicit descriptions of the frictions that make money essential. However, tractable versions usually have strong assumptions that make them ill-suited for discussing some policy questions, especially those concerning changes in the money supply. Hence most policy analysis uses reduced-form models. We propose a framework that attempts to bridge this gap: it is based explicitly on microeconomic frictions, but allows for interesting macroeconomic policy analyses. At the same time, the model is analytically tractable and amenable to quantitative analysis.

Abstract:
We extend simple search models of crime, unemployment, and inequality to incorporate on-the-job search. This is valuable because, although simple models are useful, on-the-job search models are more interesting theoretically and more relevant empirically. We characterize the wage distribution, unemployment rate, and crime rate theoretically, and use quantitative methods to illustrate key results. For example, we find that increasing the unemployment insurance replacement rate from 53 to 65 percent increases unemployment and crime rates from 10 and 2.7 percent to 14 and 5.2 percent. We show multiple equilibria arise for some fairly reasonable parameters; in one case, unemployment can be 6 or 23 percent, and crime 0 or 10 percent, depending on the equilibrium.

Abstract:
We extend simple search-theoretic models of crime, unemployment and inequality to incorporate on-the-job search. This is valuable because, although the simple models can be used to illustrate some important points concerning the economics of crime, on-the-job search models are more relevant empirically as well as more interesting in terms of the types of equilibria they generate. We characterize crime decisions, unemployment, and the equilibrium wage distribution. We use quantitative methods to illustrate key results, including a multiplicity of equilibria with different unemployment and crime rates, and to discuss the effects of changes in labor market and anti-crime policies.

Abstract:
We study how trading frictions in asset markets affect the distribution of asset holdings, asset prices, efficiency, and standard measures of liquidity. To this end, we analyze the equilibrium and optimal allocations of a search-theoretic model of financial intermediation similar to Duffie, Gârleanu and Pedersen (2005). In contrast with the existing literature, the model we develop imposes no restrictions on asset holdings, so traders can accommodate frictions by varying their trading needs through changes in their asset positions. We find that this is a critical aspect of investor behavior in illiquid markets. A reduction in trading frictions leads to an increase in the dispersion of asset holdings and trade volume. Transaction costs and intermediaries' incentives to make markets are nonmonotonic in trade frictions. With the entry of dealers, these nonmonotonicities give rise to an externality in liquidity provision that can lead to multiple equilibria. Tight spreads are correlated with large volume and short trading delays across equilibria. From a normative standpoint we show that the asset allocation across investors and the number of dealers are socially inefficient.

bid-ask spread, execution delay, liquidity, search, trade volume

Abstract:
We study the dynamics of liquidity provision by dealers during an asset market crash, described as a temporary negative shock to investors aggregate asset demand. We consider a class of dynamic market settings where dealers can trade continuously with each other, while trading between dealers and investors is subject to delays and involves bargaining. We derive conditions on fundamentals, such as preferences, market structure and the characteristics of the market crash (e.g., severity, persistence) under which dealers provide liquidity to investors following the crash. We also characterize the conditions under which dealers incentives to provide liquidity are consistent with market efficiency.

Abstract:
We study the dynamics of liquidity provision by dealers during an asset market crash, described as a temporary negative shock to investors' aggregate asset demand. We consider a class of dynamic market settings where dealers can trade continuously with each other, while trading between dealers and investors is subject to delays and involves bargaining. We derive conditions on fundamentals, such as preferences, market structure and the characteristics of the market crash (e.g., severity, persistence) under which dealers provide liquidity to investors following the crash. We also characterize the conditions under which dealers' incentives to provide liquidity are consistent with market efficiency.

liquidity, asset inventories, execution delays, search, bargaining

Abstract:
This paper pursues a line of Cass and Shell, who advocate monetary models that are genuinely dynamic and fundamentally disaggregative and incorporate diversity among households and variety among commodities. Recent search-theoretic models fit this description. We show that, like overlapping generations models, search models generate interesting dynamic equilibria, including cycles, chaos, and sunspot equilibria. This helps us understand how alternative models are related, and lends support to the notion that endogenous dynamics and uncertainty matter, perhaps especially in monetary economies. We also suggest such equilibria in search models may be more empirically relevant than in some other models.

Abstract:
This paper studies the effects of anticipated inflation on aggregate output and welfare within a search-theoretic framework. We allow money-holders to choose the intensities with which they search for trading partners, so inflation affects the frequency of trade as well as the quantity of output produced in each trade. We consider the standard pricing mechanism for search models, i.e., ex-post bargaining, as well as a notion of competitive pricing. If prices are bargained over, the equilibrium is generically inefficient and an increase in inflation reduces buyers' search intensities, output, and welfare. If prices are posted and buyers can direct their search, search intensities are increasing with inflation for low inflation rates and decreasing for high inflation rates. The Friedman rule achieves the first best allocation and inflation always reduces welfare even though it can have a positive effect on output for low inflation rates.

search, money, inflation, welfare, output

Abstract:
We study the effects of anticipated inflation on aggregate output and welfare within a search-theoretic framework. We consider two pricing mechanisms: ex post bargaining and a notion of competitive pricing. Under bargaining, the equilibrium is generically inefficient and an increase in inflation reduces buyers' search intensities, output, and welfare. If prices are posted and buyers can direct their search, search intensities are increasing with inflation for low inflation rates and decreasing for high inflation rates. The Friedman rule achieves the efficient allocation, and inflation always reduces welfare, although it can have a positive effect on output for low inflation rates.

Abstract:
This paper investigates how market structure affects efficiency and several dimensions of liquidity in an asset market. To this end, we generalize the search-theoretic model of financial intermediation of Darrell Duffie et al. (2005) to allow for entry of dealers and unrestricted asset holdings.

bid-ask spread, execution delay, liquidity, search, trade volume

Abstract:
This paper illustrates an alternative approach to modeling search frictions. Frictions are not assumed to exist, but are shown to arise endogenously as a distinctive feature of the set of equilibria that correspond to a particular range of parameter values. The model's spatial structure and the agents' moving decisions are explicitly spelled out, allowing the number of contacts that occur to depend on the way agents choose to locate themselves. An aggregate matching function is shown to exist, and its behavior with respect to changes in parameters such as distances between locations, the agents' payoffs, and the sizes of the population of searchers on each side of the market is completely characterized.

Abstract:
This paper proposes an aggregative model of Total Factor Productivity (TFP) in the spirit of Houthakker (1955-1956). It considers a frictional labor market where production units are subject to idiosyncratic shocks and jobs are created and destroyed as in Mortensen and Pissarides (1994). An aggregate production function is derived by aggregating across production units in equilibrium. The level of TFP is explicitly shown to depend on the underlying distribution of shocks as well as on all the characteristics of the labor market as summarized by the job-destruction decision. The model is also used to study the effects of labor-market policies on the level of measured TFP.

Abstract:
This paper proposes an aggregative model of total factor productivity (TFP) in the spirit of Houthakker (1955-1956). It considers a frictional labour market where production units are subject to idiosyncratic shocks and jobs are created and destroyed as in Mortensen and Pissarides (1994). An aggregate production function is derived by aggregating across micro-production units in equilibrium. The level of TFP is explicitly shown to depend on the underlying distribution of shocks as well as on all the characteristics of the labour market as summarized by the job-destruction decision. The model is also used to study the effects of labour-market policies on the level of measured TFP.

Abstract:
We investigate how trading frictions in asset markets affect portfolio choices, asset prices and efficiency. We generalize the search-theoretic model of financial intermediation of Duffie, Gârleanu and Pedersen (2005) to allow for more general preferences and idiosyncratic shock structure, unrestricted portfolio choices, aggregate uncertainty and entry of dealers. With a fixed measure of dealers, we show that a steady-state equilibrium exists and is unique, and provide a condition on preferences under which a reduction in trading frictions leads to an increase in the price of the asset. We also analyze the effects of trading frictions on bid-ask spreads, trade volume and the volatility of asset prices, and find that the asset allocation is constrained-inefficient unless investors have all the bargaining power in bilateral negotiations with dealers. We show that the dealers' entry decision introduces a feedback that can give rise to multiple equilibria, and that free-entry equilibria are generically inefficient.

asset prices, bid-ask spread, execution delay, liquidity, search, trade volume

Abstract:
We study the efficiency of dealers' liquidity provision and the desirability of policy intervention in over-the-counter (OTC) markets during crises. Our theory emphasizes two key frictions in OTC markets: finding counterparties takes time, and trade is bilateral, with quantities and prices determined by bargaining. We model a crisis as a negative shock to investors' asset demands that lasts until a random recovery time. In this context, dealers can provide liquidity to outside investors by acting as counterparties in trades and by accumulating asset inventories. We find that, when frictions are severe, even well capitalized dealers may not find it optimal to accumulate inventories, given that investors choose asset positions that require small reallocations. In such circumstances, welfare can increase if the government steps in, purchases private assets on its own account, and resells them when the economy recovers.

Abstract:
We construct a model in which capital competes with fiat money as a medium of exchange, and establish conditions on fundamentals under which fiat money can be both valued and socially beneficial. When the socially efficient stock of capital is too low to provide the liquidity agents need, they overaccumulate productive assets to use as media of exchange. When this is the case, there exists a monetary equilibrium that dominates the nonmonetary one in terms of welfare. Under the Friedman rule, fiat money provides just enough liquidity so that agents choose to accumulate the same capital stock a social planner would.

commodity money, fiat money

Abstract:
Search-theoretic models of monetary exchange are based on explicit descriptions of the frictions that make money essential. However, tractable versions of these models typically need strong assumptions that make them ill-suited for studying monetary policy. We propose a framework based on explicit micro foundations within which macro policy can be analyzed. The model is both analytically tractable and amenable to quantitative analysis. We demonstrate this by using it to estimate the welfare cost of inflation. We find much higher costs than the previous literature: our model predicts that going from 10% to 0% inflation can be worth between 3% and 5% of consumption.

Abstract:
We study the efficiency of dealers' liquidity provision and the desirability of policy intervention in over-the-counter (OTC) markets during crises. Our theory emphasizes two key frictions in OTC markets: finding counterparties takes time, and trade is bilateral, with quantities and prices determined by bargaining. We model a crisis as a negative shock to investors' asset demands that lasts until a random recovery time. In this context, dealers can provide liquidity to outside investors by acting as counterparties in trades and by accumulating asset inventories. We find that, when frictions are severe, even well capitalized dealers may not find it optimal to accumulate inventories, given that investors choose asset positions that require small reallocations. In such circumstances, the market allocative efficiency can increase if the government steps in, purchases private assets on its own account, and resells them when the economy recovers.

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Abstract:
This paper studies the effects of anticipated inflation on aggregate output and welfare within a search-theoretic framework. We allow money-holders to choose the intensities with which they search for trading partners, so inflation affects the frequency of trade as well as the quantity of output produced in each trade. We consider the standard pricing mechanism for search models, i.e. ex-post bargaining, as well as a notion of competitive pricing. If prices are bargained over, the equilibrium is generically inefficient and an increase in inflation reduces buyers search intensities, output and welfare. If prices are posted and buyers can direct their search, search intensities are increasing with inflation for low inflation rates and decreasing for high inflation rates. The Friedman Rule achieves the first best allocation and inflation always reduces welfare even though it can have a positive effect on output for low inflation rates.

Abstract:
I develop an asset-pricing model in which financial assets are valued for their liquidity-the extent to which they are useful in facilitating exchange-as well as for being claims to streams of consumption goods. The implications for average asset returns, the equity-premium puzzle and the risk-free rate puzzle, are explored in a version of the model that nests the work of Mehra and Prescott (1985).

Asset Pricing, Liquidity, Exchange, Equity Premium, Risk-Free Rate

Abstract:
We develop an equilibrium search model that incorporates job-to-job transitions, exhibits instances of replacement hiring, and conceptually distinguishes between job and worker flows. We propose a notion of competitive equilibrium for random-matching environments and study the extent to which it achieves an efficient allocation of resources. The model can be used to study how the permanent incomes and employment states of individual workers evolve over time, the amount of worker turnover in excess of job reallocation, the lengths of job tenures and unemployment durations, and the size and persistence of changes in workers' incomes following displacements or job-to-job transitions.

Abstract:
Search-theoretic models of monetary exchange are based on explicit descriptions of the frictions that make money essential. However, tractable versions of these models typically make strong assumptions that render them ill suited for monetary policy analysis. We propose a new framework, based on explicit micro foundations, within which macro policy can be studied. The framework is analytically tractable and easily quantifiable. We calibrate the model to standard observations and use it to measure the cost of inflation. We find that going from 10 percent to 0 percent inflation is worth between 3 and 5 percent of consumption - much higher than previous estimates.

Abstract:
This paper introduces a standard neoclassical production function in an equilibrium search model of the labour market, in order to analyse the effects that changes in the "exogenous" rental rate of capital have on the unemployment rate. When the number of firms is kept fixed, an increase in the rental rate affects unemployment only through its impact on selectivity, with the direction of the change depending on the size of the worker?s unemployment benefits relative to the firm's search costs. Regardless of the behaviour of selectivity, when the number of firms is determined endogenously, an increase in the rental rate always increases unemployment through a process of job destruction.