We examine a situation in which insurance is characterized by moral hazard. When market insurance is provided, supplementary mutual assistance between family and friends (unobservable to market insurers) will occur. When nonmarket insurers have no better information than market insurers, the mutual assistance not only crowds out market insurance but is also harmful and therefore dysfunctional. Alternatively, when nonmarket insurers can observe each other's effort perfectly, mutual assistance is beneficial. These results point to the potential importance of peer-monitoring mechanisms in mitigating moral hazard.

This paper considers the modeling of road congestion subject to peak-load demand. The standard model contains ambiguities and is poorly specified. These problems can be eliminated by working with a structural model that explicitly treats the congestion technology and drivers' behavioral decisions. The paper provides a detailed analysis of a particular structural model--William Vickrey's model of bottleneck congestion in the morning rush-hour auto commute, extended to treat elastic (i.e., price-sensitive) demand--and examines some economic implications of the structural approach.

We examine a situation in which insurance is characterized by moral hazard. When market insurance is provided, supplementary mutual assistance between family and friends (unobservable to market insurers) will occur. When nonmarket insurers have no better information than market insurers, the mutual assistance not only crowds out market insurance but is also harmful and therefore dysfunctional Alternatively, when nonmarket insurers can observe each other's effort perfectly, mutual assistance is beneficial These results point to the potential importance of peer-monitoring mechanisms in mitigating moral hazard.

When workers' search efforts are unobservable, the provision of insurance against firm-specific shocks adversely affects their incentives to find better jobs. In consequence, the equilibrium contract prescribes low wages and underemployment to encourage workers to leave low-productivity firms; and it employs both quits and layoffs to induce separations, with the mix depending both on the relative efficiency of on- and off-the-job search and on the search-incentive effects of layoffs.

This paper deals with the cost-benefit valuation of urban land in residential and road use, when there is flow congestion in transportation and congestion tolls are not imposed. Conventional procedures for determining the shadow value of land in road or residential use ignore certain general equilibrium effects, and always overstate the true values. To illustrate the correct procedures, an urban simulation model is used to calculate shadow rents of land as a function of location. The model is more realistic than most theoretical urban models, particularly in its treatment of congestion.