Knowledge that Transforms

This paper documents the widely perceived but little investigated notion that teachers today are less qualified than they once were. Evidence of a marked decline in the quality of young women going into teaching between 1960 and 1990 is presented, using standardized test scores, undergraduate institution selectivity, and positive assortative mating characteristics as indicators of quality. In contrast, the quality of young women becoming professionals increased. The Roy model of self-selection highlights how occupational differences in the returns to skill determine teacher quality. Estimates suggest the significance of increasing professional opportunities for women in affecting the decline in teacher quality.

In this paper we consider a nonparametric regression model that admits a mix of continuous and discrete regressors, some of which may in fact be redundant (that is, irrelevant). We show that, asymptotically, a data-driven least squares cross-validation method can remove irrelevant regressors. Simulations reveal that this “automatic dimensionality reduction” feature is very effective in finite-sample settings.

This paper examines dynamic pricing behavior in Canadian retail gasoline markets. I find three distinct pricing patterns: cost-based pricing, sticky pricing, and sharp asymmetric retail price cycles that resemble the Edgeworth cycles of Maskin and Tirole (1988). I use a Markov-switching regression to estimate the prevalence of the regimes and the structural characteristics of the cycles themselves. I find cycles are more prevalent when there are more small firms and are accelerated and amplified with very many small firms. In markets with few small firms, sticky pricing dominates. The findings are consistent with the theory of Edgeworth cycles.

Social commentators have pointed to problems of workers who face “time stress”—an absence of sufficient time to accomplish all their tasks. An economic theory views time stress as reflecting how tightly the time constraint binds households. Time stress will be more prevalent in households with higher full earnings and whose members work longer in the market or on “required” homework. Evidence from Australia (2001), Germany (2002), the United States (2003), and Korea (1999) corroborates the theory. Adults in households with higher earnings perceive more time stress for the same amount of time spent in market work and household work. The importance of higher full earnings in generating time stress is not small, particularly in the United States—much is “yuppie kvetch.”

Of the ten million uninsured children in 1996, nearly half were eligible for public health insurance (Medicaid) but not enrolled. In response, policy efforts to reduce the uninsured have shifted from expanding Medicaid eligibility to increasing take-up among those eligible. However, little is known about the reasons poor families fail to enroll or the consequences. Using a unique data set I find that information and administrative costs are important barriers to enrollment, especially for Hispanics and Asians. In addition, enrolling children in Medicaid before they get sick promotes the use of preventative care, reduces the need for hospitalization, and improves health.

The random assignment of cadets to social groups at West Point provides a rare opportunity to highlight potentially misleading estimates of social group effects found in many studies. Estimates of contemporaneous group effects in human capital production are typically positive and significant; however, evidence in this study suggests that occurrences common to a group may account for much of this correlation. Models that address these biases provide little evidence of group effects in academic performance, although there is evidence of group influences in choice outcomes such as the selection of academic major and the decision to remain in the Army.

Previous research finds a systematic decrease in consumption at retirement, a finding that is inconsistent with the life cycle/permanent income hypothesis if retirement is an expected event. In this paper, we use workers' subjective beliefs about their retirement dates as an instrument for retirement. After demonstrating that subjective retirement expectations are strong predictors of subsequent retirement decisions, we still find a consumption decline at retirement for workers who retire when expected. However, our estimates of this consumption fall are about a third less than those found when we instead rely on the instrumental variables strategy used in prior studies.

Peer effects have figured prominently in debates on school vouchers, desegregation, ability tracking, and antipoverty programs. Compelling evidence of their existence remains scarce for plaguing endogeneity issues such as selection bias and the reflection problem. This paper is among the first to firmly establish the link between peer performance and student achievement, using a unique data set from China. We find strong evidence that peer effects exist and operate in a positive and nonlinear manner; reducing the variation of peer performance increases achievement; and our semiparametric estimates clarify the trade-offs facing policymakers in exploiting positive peer effects to increase future achievement.

This paper analyzes the pricing behavior of electricity generating firms in the restructured California market from its inception in April 1998 until its collapse in late 2000. Using detailed firm-level data, I find that conduct is fairly consistent with a Cournot pricing game for much of the sample. In summer and fall 2000, the market was slightly less competitive, yet the dramatic rise in prices was more driven by changes in costs and demand than by changes in firm conduct. The five large nonutility generators raised prices slightly above unilateral market-power levels in 2000, but fell far short of colluding on the joint monopoly price.

We show that public investment is dramatically higher in countries with low-quality governance and limited political checks and balances or no competitive elections. This result is robust to a number of specifications. The most plausible interpretation of these results is that these governments use public investment as a vehicle to increase their rent-seeking. This evidence suggests that efforts to increase public investment in countries with weak governance, or to measure the growth effects of productive public investment using only observed measures of public investment, should be undertaken with caution.