Abstract We study the effects of a credit crunch on consumer spending in a heterogeneousagent incomplete-market model. After an unexpected permanent tightening in consumers' borrowing capacity, some consumers are forced to deleverage and others increase their precautionary savings. This depresses interest rates, especially in the short run, and generates an output drop, even with flexible prices. The output drop is larger with nominal rigidities, if the zero lower bound prevents the interest rate from adjusting downwards. Adding durable goods to the model, households take larger debt positions and the output response may be larger.

This paper provides a critical survey of the large literature on the life cycle model of consumption, both from an empirical and a theoretical point of view. It discusses several approaches that have been taken in the literature to bring the model to the data, their empirical successes, and their failures. Finally, the paper reviews a number of changes to the standard life cycle model that could help solve the remaining empirical puzzles. 1.

This paper studies optimal monetary policy in a model where aggregate fluctuations are driven by the private sector’s uncertainty about the economy’s fundamentals. Infor-mation on aggregate productivity is dispersed across agents and there are two aggregate shocks: a standard productivity shock and a “noise shock ” affecting public beliefs about aggregate productivity. Neither the central bank nor individual agents can distinguish the two shocks when they are realized. Despite the lack of superior information, monetary policy can affect the economy’s relative response to the two shocks. As time passes, better information on past fundamentals becomes available. The central bank can then adopt a backward-looking policy rule, based on more precise information about past shocks. By announcing its response to future information, the central bank can influence the expected real interest rate faced by forward-looking consumers with different beliefs and thus affect the equilibrium allocation. If the announced future response is sufficiently aggressive, the central bank can completely eliminate the effect of noise shocks. However, this policy is typically suboptimal, as it leads to an excessively compressed distribution of relative prices. The optimal monetary policy balances the benefits of aggregate stabilization with the costs in terms of cross-sectional efficiency.

We propose a simple summary statistic for a nation’s flow of welfare, measured as a consumption equivalent, and compute its level and growth rate for a broad set of countries. This welfare metric combines data on consumption, leisure, inequality, and mortality. Although it is highly correlated with per capita GDP, deviations are often economically significant: Western Europe looks considerably closer to U.S. living standards, emerging Asia has not caught up as much, and many African and Latin American countries appear farther behind. Each of the four components we introduce plays an important role in accounting for these differences.

How well do people share risk? Standard risk-sharing regressions assume that any variation in households ’ risk preferences is uncorrelated with variation in the cyclicality of income. I combine administrative and survey data to show that this assumption is questionable: Risk-tolerant workers hold jobs where earnings carry more aggregate risk. The correlation makes risk-sharing regressions in the previous literature too pessimistic. I derive techniques that eliminate the bias, apply them to U.S. data, and find that the effect of idiosyncratic income shocks on consumption is practically small and statistically difficult to distinguish from zero.

We study the welfare cost of market incompleteness in a generalized Bewley model where idiosyncratic risk takes the form of entrepreneurial productivity shocks. Market incompleteness in our framework has two dimensions. First, in the Bewley tradition, only a limited set of instruments for consumption smoothing is available. Second, entrepreneurs’ capital rental is subject to collateral constraints. As is well-known, it is harder to self-insure against more persistent shocks, and the welfare cost of missing consumption insurance increases with shock persistence. On the other hand, with collateral constraints, an increase in shock persistence leads to better allocation of production factors through entrepreneurs ’ self-financing, and the welfare cost of imperfect capital rental markets decreases with shock persistence. The overall welfare cost of market incompleteness can be increasing, decreasing, or even non-monotone in shock persistence, depending on the relative strengths of its two components—the cost of missing insurance and the cost of imperfect capital markets.

The steady state general equilibrium and welfare consequences of a Medicare buy-in program, optional for those aged 55-64, is evaluated in a calibrated life-cycle econ-omy with incomplete markets. Incomplete markets and adverse selection create a potential welfare improving role for health insurance reform. We find that adverse se-lection eliminates any market for a Medicare buy-in if it is offered as an unsubsidized option to individual private health insurance. The subsidy needed to bring the number of uninsured to less than 5 percent of the target population could be financed by an increase in the labor income tax rate of just 0.03 to 0.18 percent depending on how the program is implemented.

This paper was previously circulated as "The Wealth Distribution in Bewley Economies with Investment Risk." Thanks to Ben Moll for kindly providing us with very useful detailed comments and to Yi Lu for precious suggestions regarding various computational aspects.

This paper analyzes the welfare effects of the change in unemployment insurance benefits in three general equilibrium incomplete market models. In particular, it decomposes the total effect for each individual into different factors. In all of the models that I consider, the consumers face an uninsurable unemployment risk, can save in a interest-bearing asset, and face a borrowing constraint. I find that (i) in the models that are calibrated to the U.S. economy, the welfare benefit of having access to unemployment insurance above the current U.S. level is very limited, (ii) the changes in equilibrium prices tend to create a conflict of interest between poor and rich consumers, (iii) considering the endogenous reaction of the equilibrium unemployment rate to unemployment insurance benefit is important when considering the welfare effect of the change in equilibrium prices, and (iv) an unanticipated change in unemployment insurance benefits involves implicit transfers. Details of the model matter substantially in shaping the total welfare outcome, both through the direct effect on individuals and through the general equilibrium effect.

We study Ramsey policies and optimal monetary policy rules in a model with sticky prices and unionized labour markets. Collective wage bargaining and unions monopoly power dampen wage ‡uctuations and amplify employment ‡uctuations relatively to a DNK model. The optimal monetary policy must trade-o ¤ between stabilizing in‡ation and reducing ine ¢ cient unemployment ‡uctuations induced by unions’monopoly power. In this context the monetary authority uses in‡ation as a tax on unions’rents. The optimal monetary policy rule targets unemployment alongside in‡ation.