Do marital prospects dissuade unmarried fertility?

Unmarried fertility was a lot lower in the 1970s than in the 1990s. It was also the case that unmarried mothers had much lower marriage rates than non-mothers, a differential that has largely vanished over time. Could this marriage-market penalty have been strong enough to explain why unmarried fertility rates were lower then? To explore this issue, we introduce a new model of fertility and marriage, based on directed search. Relative to the existing literature, the essential contributions of the model are to allow for accumulation of children over the lifecycle and for the marriage of single mothers. We use the model, in conjunction with US survey data, to explore the impact of marital prospects on the fertility decisions of unmarried women. We find that the decline, from the 1970s to 1995, in marriage rates of unmarried women with no children, can account for the dramatic rise in unmarried women’s share of births over that period

The Value of a Reputation System

This paper explores the trade-off between the short-term benefits of false quality advertisements against the longer term costs of reputation damage. A directed search model is constructed in which submarkets are created by the advertisements and reputations of sellers. A reputation system links misleading advertisements in the present period to a lower reputation in the next period. We show that a reputation system always increases the prices of high quality products and directs search more accurately towards the sellers with such products. We also show that buyers are hurt by a reputation system if the market is thin -- has few sellers -- because the equilibrium increase in prices is greater than the equilibrium increase in the quality of trade. Finally, we show that a reputation system which screens for honesty increases social welfare by making sellers more truthful. However, we also show that a reputation for honesty is not always highly valued and that an alternative reputation system which screens for type can be more effective.reputation systems, directed search

Informational Intermediation and Competing Auctions

We examine the effects of provision of information about seller qualities by a third-party in a directed search model with heterogeneous sellers, asymmetric information, and where prices are determined ex post. The third party separates sellers into quality-differentiated groups and provides this information to some or all buyers. We show that this always raises total welfare, even if it causes the informed buyers not to trade with low quality sellers. However, buyers and some sellers may be made worse off in equilibrium. We also examine the provision of information by a profit maximizing monopoly, and show that it may have an incentive to overinvest in the creation of information relative to the social optimum.

Competitive Auctions: Theory and Application

The theory of competitive auctions offers a coherent framework for modelling coordination frictions as a non-cooperative game. The theory represents an advancement over cooperative approaches that make exogenous assumptions about how output is divided between buyers and sellers and about the forces that bring buyers and sellers into local markets. Moreover, unlike price posting models, which fix the terms of trade prior to matching, competitive auction models have a bidding process that allocates the good (or service) to the highest valuation bidder at a price equal to the second highest valuation. Therefore, the competing auction model is more robust to problems in which there are heterogenous valuations. This paper develops the theory of competitive auctions and applies it to a number of practical problems in microeconomics, labor economics, industrial organization, investment theory and monetary economics.

Loschmidt-amplitude wave function spectroscopy and the physics of dynamically driven phase transitions

We introduce the Loschmidt amplitude as a powerful tool to perform spectroscopy of generic many-body wave functions and use it to interrogate the wave function obtained after ramping the transverse field quantum Ising model through its quantum critical point. Previous results are confirmed and a more complete understanding of the population of defects and of the effects of magnon-magnon interaction or finite-size corrections is obtained. The influence of quantum coherence is clarified

Simple Reputation Systems

This paper develops a model of simple 'reputation systems' that monitor and publish information about the behavior of sellers in a market with search frictions and asymmetric information. The reputations created by these systems influence the equilibrium search patterns of buyers and thus provide for market-based 'punishment' of bad behavior. Our model allows us to determine the effects of the introduction of a reputation system on the behavior and welfare of buyers and sellers in such a market. We show that a simple reputation system that rewards honesty can enhance welfare by allowing good sellers to truthfully signal their type. However, we also show that in some cases the same reputation system is prone to strategic manipulation by sellers who always have low quality products. In this case, we show that an alternative simple reputation system that screens for type can be superior

Dynamical regimes of dissipative quantum systems

We reveal several distinct regimes of the relaxation dynamics of a small quantum system coupled to an environment within the plane of the dissipation strength and the reservoir temperature. This is achieved by discriminating between coherent dynamics with damped oscillatory behavior on all time scales, partially coherent behavior being nonmonotonic at intermediate times but monotonic at large ones, and purely monotonic incoherent decay. Surprisingly, elevated temperature can render the system `more coherent' by inducing a transition from the partially coherent to the coherent regime. This provides a refined view on the relaxation dynamics of open quantum systems.Comment: 5 pages, 3 figure

Spectral properties of one-dimensional Fermi systems after an interaction quench

We show that the single-particle spectral properties of gapless one-dimensional Fermi systems in the Luttinger liquid state reached at intermediate times after an abrupt quench of the two-particle interaction are highly indicative of the unusual nonequilibrium nature of this state. The line shapes of the momentum integrated and resolved spectral functions strongly differ from their ground state as well as finite temperature equilibrium counterparts. Using an energy resolution improved version of radio-frequency spectroscopy of quasi one-dimensional cold Fermi gases it should be possible to experimentally identify this nonequilibrium state by its pronounced spectral signatures.Comment: 5 pages, 3 figure