Knowledge that Transforms

This paper suggests that decision-making under uncertainty is, at least partly, case-based. We propose a model in which cases are primitive, and provide a simple axiomatization of a decision rule that chooses a “best” act based on its past performance in similar cases. Each act is evaluated by the sum of the utility levels that resulted from using this act in past cases, each weighted by the similarity of that past case to the problem at hand. The formal model of case-based decision theory naturally gives rise to the notions of satisficing decisions and aspiration levels.

A model of the labor market under firing restrictions and endogenous quits is constructed. It is shown that in the spirit of Blanchard and Summers, the model can generate multiple equilibria for plausible parameter values, with a low quits/high unemployment equilibrium coexisting with a high quits/low unemployment equilibrium.

Market responses to legislative reforms often mitigate the expected gains that reformers promise in legislation. Contemporaries hailed workers' compensation as a boon to workers because it raised the amount of postaccident compensation paid to injured workers. Despite the large gains to workers, employers often supported the legislation. Analysis of several wage samples from the early 1900s shows that employers were able to pass a significant part of the added costs of higher postaccident compensation on to some workers in the form of reductions in wages. The size of the wage offsets, however, was smaller for union workers.

This paper shows that previous analyses of IRA-type plans that seek to encourage household saving have miscalculated their effect on tax revenue and therefore on national saving by ignoring their favorable impact on corporate tax payments. Recognizing the important effects of IRA plans on corporate tax revenue changes previous conclusions about the revenue loss in a fundamental way. The revenue loss associated with IRAs either is much smaller than has generally been estimated or is actually a revenue gain.

This paper proposes a theory of supply shocks, or shifts in the short-run Phillips curve, based on relative-price changes and frictions in nominal price adjustment. When price adjustment is costly, firms adjust to large shocks but not to small shocks, and so large shocks have disproportionate effects on the price level. Therefore, aggregate inflation depends on the distribution of relative-price changes: inflation rises when the distribution is skewed to the right, and falls when the distribution is skewed to the left. We show that this theoretical result explains a large fraction of movements in postwar U. S. inflation. Moreover, our model suggests measures of supply shocks that perform better than traditional measures, such as the relative prices of food and energy.

Decisions under uncertainty depend not only on the degree of uncertainty but also on its source, as illustrated by Ellsberg's observation of ambiguity aversion. In this article we propose the comparative ignorance hypothesis, according to which ambiguity aversion is produced by a comparison with less ambiguous events or with more knowledgeable individuals. This hypothesis is supported in a series of studies showing that ambiguity aversion, present in a comparative context in which a person evaluates both clear and vague prospects, seems to disappear in a noncomparative context in which a person evaluates only one of these prospects in isolation.

The determinants of bargaining power and price formation in a dynamic exchange market where new traders enter randomly over time are studied. When agents on the long side of the market possess the option to wait for the arrival of future partners, the terms of trade in the spot market must honor the value of this option. The equilibrium terms of trade are expressed in intuitive closed-form equations that highlight the distinct influences of short-run spot-market conditions and long-run market demographics.

This paper provides a simple framework showing that the extent of competition in credit markets is important in determining the value of lending relationships. Creditors are more likely to finance credit-constrained firms when credit markets are concentrated because it is easier for these creditors to internalize the benefits of assisting the firms. The paper offers evidence from small business data in support of this hypothesis.

This paper presents new results on the size, frequency, and synchronization of price changes for twelve selected retail goods over the past 35 years. Three basic facts about the data are uncovered. First, nominal prices are typically fixed for more than one year, although the time between changes is very irregular. Second, prices change more often during periods of high overall inflation. Third, when prices do change, the sizes of the changes are widely dispersed. Both “large” and “small” changes occur for the same item, and the sizes of these changes do not closely depend on overall inflation.