What to Do at Low Doses: A Bounding Approach for Economic Analysis

To quantify the health benefits of environmental policies, economists generally require estimates of the reduced probability of illness or death. For policies that reduce exposure to carcinogenic substances, these estimates traditionally have been obtained through the linear extrapolation of experimental dose-response data to low-exposure scenarios as described in the U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment (1986). In response to evolving scientific knowledge, EPA proposed revisions to the guidelines in 1996. Under the proposed revisions, dose-response relationships would not be estimated for carcinogens thought to exhibit nonlinear modes of action. Such a change in cancer-risk assessment methods and outputs will likely have serious consequences for how benefit-cost analyses of policies aimed at reducing cancer risks are conducted. Any tendency for reduced quantification of effects in environmental risk assessments, such as those contemplated in the revisions to EPA's cancer-risk assessment guidelines, impedes the ability of economic analysts to respond to increasing calls for benefit-cost analysis. This article examines the implications for benefit-cost analysis of carcinogenic exposures of the proposed changes to the 1986 Guidelines and proposes an approach for bounding dose-response relationships when no biologically based models are available. In spite of the more limited quantitative information provided in a carcinogen risk assessment under the proposed revisions to the guidelines, we argue that reasonable bounds on dose-response relationships can be estimated for low-level exposures to nonlinear carcinogens. This approach yields estimates of reduced illness for use in a benefit-cost analysis while incorporating evidence of nonlinearities in the dose-response relationship. As an illustration, the bounding approach is applied to the case of chloroform exposure.     

Benchmark Analysis: Shopping with Proper Confidence

We discuss the issue of using benchmark doses for quantifying (excess) risk associated with exposure to environmental hazards. The paradigm of low-dose risk estimation in dose-response modeling is used as the primary application scenario. Emphasis is placed on making simultaneous inferences on benchmark doses when data are in the form of proportions, although the concepts translate easily to other forms of outcome data.     

MEANINGFUL REGRESSION AND ASSOCIATION MODELS FOR CLUSTERED ORDINAL DATA

Many proposed methods for analyzing clustered ordinal data focus on the regression model and consider the association structure within a cluster as a nuisance. However, the association structure is often of equal interest—for example, temporal association in longitudinal studies and association between responses to similar questions in a survey. We discuss the use, appropriateness, and interpretability of various latent variable and Markov models for the association structure and propose a new structure that exploits the ordinality of the response. The models are illustrated with a study concerning opinions regarding government spending and an analysis of stability and change in teenage marijuana use over time, where we reveal different behavioral patterns for boys and girls through a comprehensive investigation of individual response profiles.     

National survey evidence on disasters and relief: Risk beliefs, self-interest, and compassion

A nationally representative sample of respondents estimated their fatality risks from four types of natural disasters, and indicated whether they favored governmental disaster relief. For all hazards, including auto accident risks, most respondents assessed their risks as being below average, with one-third assessing them as average. Individuals from high-risk states, or with experience with disasters, estimate risks higher, though by less than reasonable calculations require. Four-fifths of our respondents favor government relief for disaster victims, but only one-third do for victims in high-risk areas. Individuals who perceive themselves at higher risk are more supportive of government assistance.     

Compatibility,Leisure, and Satisfaction in Marital Relationships

This study challenges the prevailing view that marital companionship promotes marital satisfaction. By following a cohort of married couples for over a decade and by incorporating several methodological improvements—such as refining the measurement of marital satisfaction, determining how much spouses enjoy doing the leisure activities they pursue together and apart, and using diary data to portray marital leisure patterns—we found that the association between companionship and satisfaction is less robust than previously believed, and that it depends on how often spouses pursue activities that reflect their own and their partner's leisure preferences. Over time, involvement in leisure liked by husbands but disliked by wives, whether as a couple or by husbands alone, is both a cause and a consequence of wives' dissatisfaction.     

Betrayal and repetition: Understanding aggression in sexually abused girls

Betrayal by a significant object is seen as primary in causing behavioral and emotional disturbances in incest victims, leading to a pervasive identification with the aggressor and disturbances in object relations development. Identification with the aggressor is understood not as a uniform defense mobilized against a specific affect but as a complex compromise formation which defends against anxiety, while also providing libidinal, aggressive and superego gratifications. Far from simply attempting to overcome the past, identifications thus preserve affects that have become pleasurable and self-defining. Two case studies of adolescent girls illustrate how treatment can help victims recognize and begin to forego the sadomasochistic pleasure derived from these identifications, a relinquishment necessary for true mastery.     

Factors Associated with the Development of Nonmetropolitan Growth Nodes in Producer Services Industries, 1980–1990*

Abstract Over the 1980–1990 period, employment in producer services industries in the nonmetropolitan United States increased substantially. This growth resulted in the development of nonmetropolitan growth nodes in producer services industries. A growth node refers to a nonmetropolitan area that contains a greater than average concentration of employment in a particular industry sector relative to other nonmetropolitan areas. Moreover, this industry concentration not only increases over time, but also represents an important source of employment growth within the area. With nonmetropolitan counties as the spatial unit of analysis, 317 growth nodes in producer services industries are identified for the 1980–1990 period. Access to workers with clerical and administrative support skills, access to highly educated workers, higher earnings per employed worker, access to recreational amenities, and proximity to metropolitan areas were associated with the development of nonmetropolitan growth nodes in producer services industries during this period.