Knowledge that Transforms

We introduce a measure of the severity of violations of the revealed preference axioms, the money pump index (MPI). The MPI is the amount of money one can extract from a consumer who violates the axioms. It is also a statistical test for the hypothesis that a consumer is rational when behavior is observed with error. We present an application using a panel data set of food expenditures. The data exhibit many violations of the axioms. Mostly, the MPI for these violations is small. The MPI indicates that the hypothesis of consumer rationality cannot be rejected.

I suggest a novel theory of GATT/WTO negotiations based on Krugman’s “new trade” model. It emphasizes international production relocations and is easy to calibrate to bilateral trade data. Focusing on the major players in recent GATT/WTO negotiations, I find that it implies reasonable noncooperative tariffs as well as moderate gains from GATT/WTO negotiations.

We consider the problem of a monopolist who must sell her inventory before some deadline, facing buyers with independent private values. The seller faces a basic trade-off between imperfect price discrimination and maintaining an effective reserve price. When there is only one unit and only a few buyers, the seller essentially posts unacceptable prices up to the very end, at which point prices collapse in a series of jumps to a “reserve price” exceeding marginal cost. When there are many buyers, the seller abandons this reserve price in order to more effectively screen buyers, with prices decreasing continuously over time.

I explore the implications for asset prices and macroeconomic dynamics of shocks that improve real investment opportunities and thus affect the representative household’s marginal utility. These investment shocks generate differences in risk premia due to their heterogeneous impact on firms: they benefit firms producing investment relative to firms producing consumption goods and increase the value of growth opportunities relative to the value of existing assets. Using data on asset returns, I find that a positive investment shock leads to high marginal utility states. A general equilibrium model with investment shocks matches key features of macroeconomic quantities and asset prices.

The new-Keynesian, Taylor rule theory of inflation determination relies on explosive dynamics. By raising interest rates in response to inflation, the Fed induces ever-larger inflation, unless inflation jumps to one particular value on each date. However, economics does not rule out explosive inflation, so inflation remains indeterminate. Attempts to fix this problem assume that the government will choose to blow up the economy if alternative equilibria emerge, by following policies we usually consider impossible. The Taylor rule is not identified without unrealistic assumptions. Thus, Taylor rule regressions do not show that the Fed moved from “passive” to “active” policy in 1980.

The black-white gap in schooling among southern-born men narrowed sharply between the world wars. From 1914 to 1931, nearly 5,000 schools were constructed as part of the Rosenwald Rural Schools Initiative. Using census data and World War II records, we find that the Rosenwald program accounts for a sizable portion of the educational gains of rural southern blacks. We find significant effects on school attendance, literacy, years of schooling, cognitive test scores, and northern migration. The gains are highest in the most disadvantaged counties, suggesting that schooling treatments have the largest impact among those with limited access to education.

We study the problem of an inventor who brings to the market an innovation that can be legally imitated. Imitators may “enter” the market by imitating the innovation at a cost or by buying from the inventor the knowledge necessary to reproduce and use the invention. The possibility of contracting dramatically affects the need for patent protection. Our results show that (i) imitators wait to enter the market and the inventor becomes a temporary monopolist; (ii) the inventor sells knowledge through contracts that allow resale by the imitators; and (iii) under certain conditions, the inventor’s payoff increases with the number of imitators.

We develop a framework for studying trade in vertically and horizontally differentiated products. In our model, consumers with heterogeneous incomes and tastes purchase a homogeneous good as well as making a discrete choice of quality and variety of a differentiated product. The distribution of preferences in the population generates a nested logit demand structure. These demands are such that the fraction of consumers who buy a higher-quality product rises with income. We use the model to study the pattern of trade between countries that differ in size and income distributions but are otherwise identical. Trade―which is driven primarily by demand factors―derives from "home market effects" in the presence of transport costs. The model helps to explain why richer countries export higher-quality goods. It provides a tractable tool for studying the welfare consequences of trade, transport costs, and trade policy for different income groups in an economy.