Knowledge that Transforms

This paper examines the allocative performance of rotating savings and credit associations (roscas), a financial institution which is observed world-wide. We develop a model in which individuals save for an indivisible good and study roscas which distribute funds using random allocation and bidding. The allocations achieved by the two types of rosca are compared with that achieved by a credit market and with efficient allocations more generally. We find that neither type of rosca is efficient and that individuals are better off with a credit market than a bidding rosca. Nonetheless, a random rosca may sometimes yield a higher level of ex ante expected utility to prospective participants than would a credit market.

Since the actual solution to intertemporal rational expectations models is usually not known, it is useful to have criteria for judging the accuracy of a given numerical solution. In this paper we propose a test for accuracy that is easy to implement and can be applied to a wide class of models without knowledge of the exact solution. We discuss the power of the test by simulating several models with the linear-quadratic approximation and with the method of parameterized expectations. We conclude that the test is powerful.

Changes in variance, or volatility, over time can be modelled using the approach based on autoregressive conditional heteroscedasticity (ARCH). However, the generalizations to multivariate series can be difficult to estimate and interpret. Another approach is to model variance as an unobserved stochastic process. Although it is not easy to obtain the exact likelihood function for such stochastic variance models, they tie in closely with developments in finance theory and have certain statistical attractions. This article sets up a multivariate model, discusses its statistical treatment and shows how it can be modified to capture common movements in volatility in a very natural way. The model is then fitted to daily observations on exchange rates.

Census reports can be interpreted as providing nearly exact knowledge of moments of the marginal distribution of economic variables. This information can be combined with cross-sectional or panel samples to improve accuracy of estimation. In this paper we show how to do this efficiently. We show that the gains from use of marginal information can be substantial. We also discuss how to test the compatibility of sample and marginal information.

We propose a nonparametric method for automatically selecting the number of autocovariances to use in computing a heteroskedasticity and autocorrelation consistent covariance matrix. For a given kernel for weighting the autocovariances, we prove that our procedure is asymptotically equivalent to one that is optimal under a mean-squared error loss function. Monte Carlo simulations suggest that our procedure performs tolerably well, although it does result in size distortions.

Investment is often irreversible: once installed, capital has little or no value unless used in production. This paper proposes and solves a model of sequential irreversible investment and characterizes the aggregate implications of microeconomic irreversibility and idiosyncratic uncertainty. If a large amount of idiosyncratic uncertainty is allowed for, the distributional dynamics induced by the nonlinear character of irreversible investment policies are capable of smoothing the dynamics of aggregate investment (relative to those of its forcing processes) to the extent required by U.S. data.

This paper studies incentives and loss of control in a hierarchy model which combines and generalizes the models of Williamson, Calvo-Wellisz and Keren-Levhari. In our model of the hierarchy, the levels of effort from managers and workers, the wage scales, the span of control and, in particular, the total number of tiers are all endogenous. Using optimal control techniques, we show that in the optimal hierarchy the wage scales and effort levels decrease as one moves down the hierarchy. As the hierarchy expands with no technological progress, workers exert less effort and are paid less, top managers work harder and are paid more and the wage distribution becomes increasingly skewed.