Mary F. Evans

Urban Trails and Physical Activity: A Natural Experiment

BACKGROUND The built environment in which a person lives and works is thought to have a strong influence on his or her level of physical activity. However, this belief is largely based on cross-sectional studies underlining the need for prospective studies using natural experiments. DESIGN This study adopted a quasi-experimental research design with multiple control neighborhoods and was conducted between 2005 and 2007. Data were analyzed in 2008. SETTING/PARTICIPANTS The subjects were children, adolescents, and adults in free-living conditions within one experimental and two control neighborhoods. INTERVENTION An urban greenway/trail was retrofitted in a neighborhood that lacked connectivity of the residential pedestrian infrastructure to nonresidential destinations. MAIN OUTCOME MEASURES The main outcomes were 2-hour counts of directly observed physical activity in the general neighborhood and, at the school level, active transport to school. RESULTS At the neighborhood level, the 2-hour counts of physical activity significantly increased between 2005 and 2007 (p=0.000) in the intervention neighborhood, with a median increase of 8.0 counts. The control neighborhoods had a significant decrease in counts (p=0.000). The pre- and post-intervention changes between experimental and control neighborhoods were significantly different for total physical activity (p=0.001); walking (p=0.001); and cycling (p=0.038). There was no noted change over time for active transport to school in either the intervention or control neighborhoods. CONCLUSIONS Changes to the pedestrian connectivity of the built environment infrastructure may lead to greater levels of physical activity. However, this positive effect was limited to physical activity at the neighborhood level and not to active transport to school.

Multiple-Bounded Uncertainty Choice Data as Probabilistic Intentions

The multiple-bounded uncertainty choice (MBUC) value elicitation method allows respondents to indicate qualitative levels of uncertainty, as opposed to a simple yes or no, across a range of prices. We argue that MBUC responses convey subjective probabilities. We examine the decision process of the researcher faced with estimating population parameters from MBUC sample responses. We develop her optimal decision rule based on a specified loss function. The resulting estimator accommodates uncertainty on the part of the respondent and the researcher. We illustrate the proposed estimation method using MBUC responses from the first field application of this elicitation format. The resulting framework produces stable estimates and nests alternative methods of modeling MBUC responses. (JEL Q26)

Do the Near-Elderly Value Mortality Risks Differently?

Wage hedonic models are estimated with the Health and Retirement Study to measure the risk-wage tradeoffs (value of statistical lives) for older workers. The analysis explicitly allows for multiple employment states, including retirement, using a multinomial selection model. The results suggest that the oldest and most risk-averse workers require significantly higher, not lower, compensation to accept increases in job-related fatality risks.

A Quantile Estimation Approach to Identify Income and Age Variation in the Value of a Statistical Life

In theory, heterogeneity in individual characteristics translates into variation in the marginal willingness to pay for a mortality risk reduction. Two dimensions of heterogeneity, with respect to income and age, have recently received attention due to their policy relevance. We propose a quantile regression approach to simultaneously explore these two sources of heterogeneity and their interactions within the context of the hedonic wage model, the most common revealed preference approach for obtaining value of statistical life estimates. We illustrate the approach using data from the Health and Retirement Study (HRS). We find that the impact of age on the wage-risk tradeoff varies across the wage distribution. This result indicates important interactions between age and income heterogeneity. Thus, the conventional mean hedonic wage regression, even when the mean effect is allowed to vary with age, masks important hetereogeneity.

The Developmental Effect of State Alcohol Prohibitions at the Turn of the Twentieth Century

We examine the quasi‐randomization of alcohol consumption created by state‐level alcohol prohibition laws passed in the United States in the early part of the twentieth century. Using a large dataset of World War II enlistees, we exploit the differential timing of these laws to examine their effects on adult educational attainment, obesity, and height. We find statistically significant effects for education and obesity that do not appear to be the result of pre‐existing trends. Our findings add to the growing body of economic studies that examine the long‐run impacts of in utero and childhood environmental conditions.

A Facility-Level Analysis of the Long-Term Consequences of Environmental Auditing Among Hazardous Waste Generators

Several rationales recently proposed to explain the willingness of firms to voluntarily conduct environmental audits suggest the potential for environmental audits to impact compliance outcomes in the long run. Using a unique facility-level dataset from Michigan, we examine the determinants of environmental auditing and the effects of environmental auditing on inspection frequency and long-term compliance with the U.S. Resource Conservation and Recovery Act (RCRA) among hazardous waste generators. Our empirical methodology accounts for the potential endogeneity of the audit outcome and censoring of the future compliance measure. We find that larger facilities and those subject to more stringent regulations are more likely to audit. We also find that facilities with poor compliance records are less likely to audit. However, we find no significant long-run impact of auditing on inspection frequency or RCRA compliance among these Michigan facilities.

Economic implications of hormesis: some additional thoughts

or they might involve impacts on plants or animals that people care about. Because we generally agree with his analysis and conclusions, our comments will focus on additional issues that either follow from his paper or were not completely developed. Our discussion begins by suggesting additional policy insights might be added to Hammitts description of the problems posed by hormesis by considering cases where similar phenomenon arise elsewhere in environmental economics. It also comments on the difficulties hormesis poses for benefit measurement and closes with an alternative rationale for applying the efficiency principles Hammitt discusses.

Abatement, Care, and Compliance by Firms in Financial Distress

We examine precautionary behavior, specifically compliance with environmental regulations, pollution abatement, and care spending, by firms facing two sources of insolvency risk. If poor profit or a liability triggers insolvency, then the firm forgoes a profitable future. The behavioral implications of this survival motive vary across firms. Firms for whom the principal insolvency risk is liability-related now choose precaution above the level chosen by the solvent firm. For firms whose primary insolvency risk is profit-related, the survival motive reinforces incentives for care below the solvent benchmark arising from the familiar judgment-proof effect. We also characterize how insolvency risks affect incentives to conceal adverse events linked to these choices, such as an accident or a regulatory violation. An understanding of these incentives is particularly important during recessionary periods when firms struggle to survive the downturn.

Enforcement Spillovers: Lessons from Strategic Interactions in Regulation and Product Markets

We explore mechanisms driving enforcement spillovers - when sanctions at one entity influence behavior at other entities. Our model illustrates when spillovers arise from a regulatory channel and when they arise from a channel not emphasized in the existing literature: product markets. Using facility-by-month data from Clean Water Act manufacturers, we find that penalties generate strong positive spillovers for other facilities facing the same authority. We find suggestive evidence that penalties generate negative spillovers for facilities in the same industry but facing a different authority. Results are consistent with spillovers driven by strategic interactions in both regulation and product markets.