Knowledge that Transforms

Theoretical literature shows that income uncertainty boosts saving, yet empirical work is incomplete. I test for the precautionary motive for saving using panel data. Knowing this motive's size is important for gauging the responsiveness of saving to government programs that reduce uncertainty, and for comparison to other motives, such as bequests. Most empirical studies of precautionary saving use either aggregate time-series or cross-sectional data, which cannot capture the effects of individual income uncertainty. I derive measures of total, permanent, and transitory income uncertainty from panel data—the National Longitudinal Survey—and find a strong precautionary motive. A doubling of uncertainty increases the ratio of wealth to permanent income by 29%.

This paper assesses the importance of the zero lower bound on nominal interest rates for the interest-rate channel of monetary policy. We simulate several interest-rate setting policy rules with either high or low inflation targets. We determine the extent to which the zero bound prevents real rates from falling, thus cushioning aggregate output in response to negative spending shocks. For small temporary and large permanent shocks, the output path with zero inflation lies modestly below that for higher inflation. For large shocks persisting a few quarters, differences in output paths across high- and low-inflation scenarios can be larger.

The conventional approach to estimating how fast economics converge examines the cross-economy relationship between the growth rate of per-capita output over some time period and its initial level. This approach produces consistent estimates only under highly restrictive assumptions, which are violated by the data. The paper develops an alternative approach that produces consistent estimates under weak assumptions. This approach yields estimates substantially larger than those reported in the literature and also sufficiently large to be broadly consistent with the predictions of neoclassical growth theory.

This note presents tests of the specification of univariate and bivariate ordered probit. The test is sensitive to deviations from either normality or the exogeneity of the explanatory variables. As an example, the ownership of dogs and televisions, both sources of time-intensive entertainment, is studied. The specification for dogs is not rejected, the specification for televisions is rejected at the 2.0% level, and the specification of both together is rejected at the 1.3% level.

This paper is concerned with the measurement of aggregate growth rates, where the aggregation is over time. The paper demonstrates that any mechanical procedures for computing aggregate growth rate has welfare implications, and value judgments implicit in various commonly used procedures are not appealing. A new procedure suggested in the paper captures all the essential properties of a welfare function. The methodology of the paper is applied to an analysis of growth rates of per capita GNP of 83 developing countries during the 1970–1987 period.

This paper examines the wealth mobility of a panel of mature American men between 1966 and 1981. Although greater persistence exists than within the income distribution, a sizeable degree of movement within the wealth distribution is observed. Slightly more than half of the households changed quintiles. However, the magnitude of the movement was modest, with 78% of the moves to an adjacent quintile. Movements into either extreme of the wealth distribution were relatively rare. Really big moves, from the poorest to richest group, were extremely rare, with the probability of a black making such a move within fifteen years approximately zero.

Performance may enhance survival probability. When it does, the induced lack of randomness challenges robust and unbiased inference. If survivors are sorted into two groups based on past performance, spurious persistence has been demonstrated if variance in performance is heterogeneous. However, as we show both theoretically and with simulations, if performance is categorized finely, the spurious persistence will be J-shaped; that is, at the bottom better performance in one period “predicts” worse performance for another period. We propose a simple t-test applied to the quadratic coefficient in a regression to distinguish between a spurious J-shape and monotonic patterns. Mutual funds, our example, exhibit the monotonically increasing pattern produced by true performance persistence.

This paper introduces an improved procedure for estimating capital asset price indexes. We jointly estimate conventional hedonic and repeat sales models via maximum-likelihood procedures, thereby taking advantage of the unique features of the individual models and using all the data that are available. Our model captures depreciation within the repeat sales model and accounts for serial correlation in hedonic data. The improvement in precision obtained by estimating the joint model is illustrated by smaller standard errors and narrower interval estimates for the resulting price indexes. We also carry out a simulation experiment that shows estimation errors significantly smaller using the joint estimation technique than either of the individual models or the GLS estimator of Case and Quigley (1991).

In a recent paper Lichtenberg (1994) proposes a test of the convergence hypothesis that the variance of productivity across countries decreases over time. He argues that the ratio of the variance in the first period to that in the last period of the time series is F-distributed but overlooks the dependency between these two variances. As a consequence, probabilities of committing a type II error of incorrectly rejecting the convergence hypothesis are large. This problem manifests most strongly in short time periods. Lichtenberg, for example, rejects the convergence hypothesis for a data set of 22 OECD countries over the 1960–1985 period.

Data on brothers and on fathers and sons from the National Longitudinal Survey are used to consider the impact of omitted variables and measurement errors on the economic returns to schooling. The analysis suggests that the upward bias in estimated returns due to omitted variables is likely offset by an equal downward bias resulting from measurement errors in reported schooling. Controlling for both of these potential sources of bias yields results comparable to conventional regression estimates of the economic return to schooling.