This paper investigates whether there are simple versions of the permanent income hypothesis which are consistent with the aggregate U.S. consumption and output data. Our analysis is conducted within the confines of a simple dynamic general equilibrium model of aggregate real output, investment, hours of work and consumption. We study the quantitative importance of two perturbations to the version of our model which predicts that observed consumption follows a random walk: (i) changing the production technology specification which rationalizes the random walk result, and (ii) replacing the assumption that agents' decision intervals coincide with the data sampling interval with the assumption that agents make decisions on a continuous time basis. We find substantially less evidence against the continuous time models than against their discrete time counterparts. In fact neither of the two continuous time models can be rejected at conventional significance levels. The continuous time models outperform their discrete time counterparts primarily because they explicitly account for the fact that the data used to test the models are tine averaged measures of the underlying unobserved point-in-time variables. The net result is that they are better able to accommodate the degree of serial correlation present in the first difference of observed per capita U.S. consumption.

We describe a general equilibrium model in which an agency problem arises because bankers must exert an unobserved and costly effort to perform their task. Suppose aggregate banker net worth is too low to insulate creditors from bad outcomes on their balance sheet. Then, banks borrow too much in equilibrium because there is a pecuniary externality associated with bank borrowing. Social welfare is increased by imposing a binding leverage restriction on banks. We formalize this argument and provide a numerical example.

Two modifications are introduced into the standard real-business-cycle model: habit preferences and a two-sector technology with limited intersectoral factor mobility. The model is consistent with the observed mean risk-free rate, equity premium, and Sharpe ratio on equity. In addition, its business-cycle implications represent a substantial improvement over the standard model. It accounts for persistence in output, comovement of employment across different sectors over the business cycle, the evidence of “excess sensitivity” of consumption growth to output growth, and the “inverted leading-indicator property of interest rates,” that interest rates are negatively correlated with future output.

Flow of funds; Monetary policy

We augment a standard monetary dynamic general equilibrium model to include a Bernanke-Gertler-Gilchrist financial accelerator mechanism. We fit the model to US data, allowing the volatility of cross-sectional idiosyncratic uncertainty to fluctuate over time. We refer to this measure of volatility as risk. We find that fluctuations in risk are the most important shock driving the business cycle.

We present a model embodying moderate amounts of nominal rigidities that accounts for the observed inertia in inflation and persistence in output. The key features of our model are those that prevent a sharp rise in marginal costs after an expansionary shock to monetary policy. Of these features, the most important are staggered wage contracts that have an average duration of three quarters and variable capital utilization.

Why is inflation persistently high in some periods and low in others? The reason may be the absence of commitment in monetary policy. In a standard model, absence of commitment leads to multiple equilibria, or expectation traps, even without trigger strategies. In these traps, expectations of high or low inflation lead the public to take defensive actions, which then make accommodating those expectations the optimal monetary policy. Under commitment, the equilibrium is unique and the inflation rate is low on average. This analysis suggests that institutions which promote commitment can prevent high inflation episodes from recurring.