A model of aggregate economic activity is formulated which enmphasizes the effects of borrowing constraints in the presence of uninsurable risk. An important determinant of current income level is shown to be the cross-sectional distribution of wealth. As this distribution evolves endogenously, the model is capable of producing rich dynamics from a simple specification of exogenous shocks. The model shows that this phenomena can contribute to observed price volatility. IT IS COMMONLY THOUGHT that individuals have only limited opportunities to borrow against future labor income and cannot totally insure all types of risk. It has also been suggested that such departures from the presumptive norm of frictionless, complete information capital markets may have implications for aggregate economic activity. AlthLough there has been some work analyzing the implications of borrowing constraints for individual savings behavior (18, 2, 8), there has been no systematic analysis of how such borrowing constraints will affect the time series properties of output, prices, and interest rates. In this paper, we present a completely specified infinitely lived two agent equilibrium model which emphasizes the roles of borrowing constraint and uninsured risk for affecting aggregate outcomes. Specifically we assume that agents are prohibited from ever having negative nonhuman wealth. The model has the central feature that there is no aggregate uncertainty, but each agent's own productive opportunities are stochastic. If there were a full set of Arrow- Debreu contingent claim markets each agent could attain a certain consumption stream and the resulting allocation and (implicit) relative prices would be constant through time. However, we assume that such markets do not exist. Rather, we assume that at each point in time agents may trade only the single durable asset for the single perishable consumption good. This may be interpreted either as fiat mon ay with a fixed own nominal return of zero, or as claims to productive capital which emits a fixed exogenous flow of the consumption good. We assume also that output may be produced by labor. However, only one of the two agents is productive at any instant in time. The duration of time over which a single agent is productive is assumed to be random, and, for analytical simplicity, is assumed to be generated by a Poisson counting process. The resulting allocation has the property that the agent who is not productive exchanges some of his

[This paper develops a model of labor supply for married women which takes into account both the joint decision on participation and hours, and the nonlinear shape of the budget constraint due to taxation. The model can explain the absence of observations of the tax kink by assuming the existence of optimization errors in addition to errors capturing taste variation. The estimates of the model, which are obtained with British micro data, suggest that the overall wage elasticity is about 2 and that participation is more responsive to wages than hours of work.]

Seasonally adjusted monetary aggregate data as published by the Federal Reserve, are subject to large revisions, which can be interpreted as error in the preliminary measures. Since short-run monetary policy is set for seasonally adjusted data when only preliminary estimates for recent months are available, an interesting question is: Would policy have been much different if final data had been available? For the period of the seventies, we estimate what would have been the monthly Federal Open Market Committee targets for Ml and the federal funds rate if the preliminary estimate of the rate of growth of seasonally adjusted Ml had been equal to the final one. We find that, despite their large size, revision errors seem to have little impact on the setting of targets. The results suggest that the Fed reacts to a signal in the rate of growth of Ml which is smoother than the seasonally adjusted series and less affected by revisions. Since the error associated with the revision is orthogonal to the preliminary measurement, while the noise extracted is orthogonal to the true variable (the signal), the analysis illustrates the different effects of the two alternative error-in-variable specifications.

On montre comment le test de Wald s'applique a des ensembles de restrictions d'egalite et d'inegalite et on presente la distribution, pour de grands echantillons, du test sous l'hypothese nulle

[We consider an economy in which agents may or may not communicate with each other. Coalitions can form only between linked agents. We consider two cases: agents must communicate directly to be in the same coalition or in the second case indirectly. We consider the communication to be random. The economy may then be represented by a stochastic graph; the admissible coalitions are then stochastic and thus so is the core of an economy. We demonstrate that if the probability that agents are linked with each other does not tend to zero too fast as this number increases, then the probability that a coalition will form and block any non-Walrasian allocation tends to one, as the number of agents goes to infinity.]

[The axiomatic derivation of mobility indices for first-order Markov chain models in discrete time is extended to continuous-time models. Many of the logical inconsistencies among axioms noted in the literature for the discrete time models do not arise for continuous time models. It is shown how mobility indices in continuous time Markov chains may be estimated from observations at two points in time. Specific attention is given to the case in which the states are fractiles, and an empirical example is presented.]