This paper describes a search model with a continuum of worker and job types, free entry and transferable utility. We apply a second-order Taylor expansion to characterize the equilibrium, derive the "cost of search" and show that it is decreasing in the substitutability of worker types. This cost of search is then decomposed into three components: unemployment, vacancy costs and mismatch. Our contact technology rules out congestion effects between different worker types and therefore exhibits increasing returns to scale. One third of those increasing returns in contacts are shown to be absorbed by firms and workers being more choosy. The resulting equilibrium is not efficient. Unemployment benefits can reduce the loss by serving as a search subsidy. Numerical simulations of the model show that our Taylor expansions are quite accurate.

We derive a structural index for labor market density based on the Ellison-Glaeser index for industry concentration. The labor market density index serves as a proxy for the number of workers that are potentially available for jobs in a particular area. The index is based on observed home-work location patterns. It is particularly useful for testing theories where the scale of the market matters. We apply this index to a standard wage equation and find that it explains almost half of the cross-region wage variance.

This paper characterizes the equilibrium for a large class of search models with two-sided heterogeneity and on-the-job search. Besides the well-known congestion externalities, we show that on-the-job search in combination with monopsonistic wage setting without commitment creates a “business-stealing” externality. In the absence of congestion effects, this leads to excessive vacancy creation. Under wage setting with commitment this externality is absent because when posting a wage, firms take into account the expected productivity of future workers in their current jobs. If firms are able to make and respond to counteroffers, then they will not have to pay no-quit premia and this also leads to excessive vacancy creation.

We analyse a model of equilibrium directed search in a large labour market. Each worker, observing the wages posted at all vacancies, makes a fixed, finite number of applications, a. We allow for the possibility of ex post competition should more than one vacancy want to hire the same worker. For each a, there is a unique symmetric equilibrium in which all vacancies post the same wage. When a =1, the common posted wage lies between the competitive and monopsony levels, and equilibrium is efficient. When a > 1, all vacancies post the monopsony wage. Some workers fail to find a job, some find a job at the monopsony wage, and some - those for whom there is competition - get the competitive wage. Equilibrium is inefficient when a > 1; in particular, there is excessive vacancy creation.

In this paper, we demonstrate the efficiency of seller entry in a model of competing auctions in which we allow for both buyer and seller heterogeneity. This generalizes existing efficiency results in the competitive search literature by simultaneously allowing for nonrival (many-on-one) meetings and private information.

We use a unique combination of register and survey data from Amsterdam to investigate the performance of school assignment mechanisms in practice. We find that deferred acceptance (DA) results in higher mean welfare than the adaptive Boston mechanism. This is due to students making strategic mistakes. The welfare gain of a switch from actual Boston to DA is over 90% of the welfare difference between actual Boston and optimal (proxy) Boston. Disadvantaged and lower-ability students would benefit most from such a switch.