Efficiency of Simultaneous Search

We analyze a labor search model in which workers choose their search intensity by deciding how often and where to apply for jobs. They observe firms’ wage postings prior to their decision. Due to coordination frictions a firm may not receive any applications; otherwise it is able to hire unless all its applicants have better offers. We show that in equilibrium the entry of firms, the search intensity and the number of filled vacancies are constrained efficient. Wage dispersion creates an (endogenous) safety net against unemployment that is essential for efficiency. As application costs vanish the equilibrium becomes unconstrained efficient.simultaneous search, directed search, efficient wage dispersion, modified Hosios condition, search with stable matchings

Sorting versus screening: Search frictions and competing mechanisms

In a market where sellers compete by posting trading mechanisms, we allow for a general search technology and show that its features crucially affect the equilibrium mechanism. Price posting prevails when meetings are rival, i.e., when a meeting by one buyer reduces another buyer’s meeting probability. Under price posting buyers reveal their type by sorting ex ante. Only if the meeting technology is sufficiently non-rival, price posting is not an equilibrium. Multiple buyer types then visit the same sellers who screen ex post through auctions

On the game-theoretic foundations of competitive search equilibrium.

We provide a unified directed search framework with general production and matching specifications that encompass most of the existing literature. We prove the existence of subgame perfect Nash equilibria in pure firm strategies in a finite version of the model. We use this result to derive a more complete characterization of the equilibrium set for the finite economy and to extend convergence results as the economy becomes large to general production and matching specifications. The latter extends the microfoundations for the standard market utility assumption used in competitive search models with a continuum of agents to new environments.

Identifying Sorting - In Theory

We argue that using wage data alone, it is virtually impossible to identify whether Assortative Matching between worker and firm types is positive or negative. In standard competitive matching models the wages are determined by the marginal contribution of a worker, and the marginal contribution might be higher or lower for low productivity firms depending on the production function. For every production function that induces positive sorting we can find a production function that induces negative sorting but generates identical wages. This arises even when we allow for non-competitive mismatch, for example due to search frictions. Even though we cannot identify the sign of the sorting, we can identify the strength, i.e., the magnitude of the cross-partial, and the associated welfare loss. While we show analytically that standard fixed effects regressions are not suitable to recover the strength of sorting, we propose an alternative procedure that measures the strength of sorting in the presence of search frictions independent of the sign of the sorting.sorting, assortative matching, identification, linked employer-employee data, interpretation of fixed-effects

A Model of Money with Multilateral Matching, Second Version

We develop a model of monetary exchange that avoids several common criticisms of the recent microfoundations literature. First, rather than random matching, we assume that buyers know the location of all sellers, and hence the process of finding a partner is deterministic, although trade is still stochastic since the number of buyers visiting a given seller is random. Second, given multilateral matching, rather than bargaining, we assume that goods are allocated according to second-price auctions. Third, given this mechanism, we do not have to assume agents can observe each other’s money holdings or preferences, as is necessary for tractability with bargaining. A novel result is that homogeneous buyers hold different amounts of money, leading to equilibrium price dispersion. We find the closed-form solution for the distribution of money holdings. We characterize equilibrium and efficient monetary policy.Search Theory of Money, Budget Constrained Auctions, Friedman Rule

Efficient Firm Dynamics in a Frictional Labor Market

The introduction of firm size into labor search models raises the question how wages are set when average and marginal product differ. We develop and analyze an alternative to the existing bargaining framework: Firms compete for labor by publicly posting long–term contracts. In such a competitive search setting, firms achieve faster growth not only by posting more vacancies, but also by offering higher lifetime wages that attract more workers which allows to fill vacancies with higher probability, consistent with empirical regularities. The model also captures several other observations about firm size, job flows, and pay. In contrast to bargaining models, efficiency obtains on all margins of job creation and destruction, both with idiosyncratic and aggregate shocks. The planner solution allows a tractable characterization which is useful for computational applications.labor market search, multi-worker firms, job creation and job destruction

Strategic Firms and Endogenous Consumer Emulation

Better informed consumers may be treated preferentially by firms since their consumption serves as a quality signal for other customers. For normal goods this results in wealthy individuals being treated better than poor individuals. We investigate this phenomenon in an equilibrium model of social learning with heterogeneous consumers and firms that act strategically. Consumers search for high quality firms and condition their choices on observed actions of other consumers. When they observe consumers who are more likely to have identified a high quality firm, uninformed individuals will optimally emulate those consumers. One group of consumers arises endogenously as “leaders” whose consumption behavior is emulated. Follow-on sales induce firms to give preferential treatment to these lead consumers, which reinforces their learning.Search, social learning, consumption signalling

Sorting and Decentralized Price Competition

We investigate under which conditions price competition in a market with matching frictions leads to sorting of buyers and sellers. Positive assortative matching obtains only if there is a high enough degree of complementarity between buyer and seller types. The relevant condition is root-supermodularity; i.e., the square root of the match value function is supermodular. It is a necessary and sufficient condition for positive assortative matching under any distribution of buyer and seller types, and does not depend on the details of the underlying matching function that describes the search process. The condition is weaker than log-supermodularity, a condition required for positive assortative matching in markets with random search. This highlights the role competition plays in matching heterogeneous agents. Negative assortative matching obtains whenever the match value function is weakly submodular.Competitive Search Equilibrium. Directed Search. Two-Sided Matching. Decentralized Price Competition. Root-Supermodularity.