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Robinson L.A.,Center for Health Decision Science and Center for Risk Analysis | Robinson L.A.,Center for Risk Analysis | Hammitt J.K.,Center for Health Decision Science and Center for Risk Analysis | Hammitt J.K.,Center for Risk Analysis | And 2 more authors.
Health Policy and Planning | Year: 2017

Researchers and policymakers have long been interested in developing simple decision rules to aid in determining whether an intervention is, or is not, cost-effective. In global health, interventions that impose costs per disability-adjusted life year averted less than three and one times gross domestic product per capita are often considered cost-effective and very cost-effective, respectively. This article explores the conceptual foundation and derivation of these thresholds. Its goal is to promote understanding of how these thresholds were derived and their implications, as well as to suggest options for improvement. These thresholds are intended to reflect the monetary value of the benefits to affected individuals, based on their preferences for spending on health vs spending on other goods and services. However, the current values were not rigorously derived, which means that their application may lead to inappropriate conclusions regarding which interventions should be adopted as well as misallocation of resources across health and other investments. Improving the basis for these cost-effectiveness thresholds is of particular importance in low- and middle-income countries, given the limited resources available and the significant needs of their populations. © 2016 The Author.


Alolayan M.A.,Kuwait University | Evans J.S.,Center for Risk Analysis | Evans J.S.,Cyprus International Institute for Environment and Public Health | Hammitt J.K.,Center for Risk Analysis | Hammitt J.K.,French National Institute for Agricultural Research
Environmental and Resource Economics | Year: 2015

We report stated-preference estimates of the value per statistical life (VSL) for Kuwaiti citizens obtained using an innovative test to identify respondents whose survey responses are consistent with economic theory. The consistency test requires that an individual report strictly positive willingness to pay (WTP) for mortality-risk reduction and that his responses to binary-choice valuation questions for two risk reductions be consistent with the theoretical requirement that WTP is less than but close to proportional to the change in risk reduction. Our estimates of VSL, $18–32 million, are approximately two to four times larger than values accepted for the United States. These values may reflect cultural factors as well as the substantially larger disposable income of Kuwaiti citizens. © 2015 Springer Science+Business Media Dordrecht


Rheinberger C.M.,French National Institute for Agricultural Research | Hammitt J.K.,French National Institute for Agricultural Research | Hammitt J.K.,Center for Risk Analysis
Environmental Science and Technology | Year: 2012

Fish consumption advisories instruct vulnerable consumers to avoid high mercury fish and to limit total fish intake to reduce neurotoxic risk. Consumption data from the U.S. suggest that nontarget consumers also respond to such advice. These consumers reduce exposure to mercury and other toxicants at the cost of reduction in cardioprotective fatty acids. We present a probabilistic model to assess these risk trade-offs. We use NHANES consumption data to simulate exposure to contaminants and nutrients in fish, employ dose-response relationships to convert exposure to health end points, and monetize them using benefit transfer. Our results suggest that newborns gained on average 0.033 IQ points from their mothers compliance with the prominent FDA/EPA advisory. The welfare gain for a birth cohort is estimated at $386 million. This gain could be fully offset by increments in cardiovascular risk if 0.6% of consumers aged 40 and older reduced fish intake by one monthly meal until they reached the age of 60 or if 0.1% of them permanently reduced fish intake. © 2012 American Chemical Society.


Rice G.E.,Harvard University | Hammitt J.K.,Center for Risk Analysis | Evans J.S.,Harvard University | Evans J.S.,Cyprus International Institute for the Environment and Public Health
Environmental Science and Technology | Year: 2010

We developed a probabilistic model to characterize the plausible distribution of health and economic benefits that would accrue to the U.S. population following reduction of methyl mercury (MeHg) exposure. MeHg, a known human developmental neurotoxicant, may increase fatal heart attack risks. Model parameters reflect current understanding of the relationships between MeHg intake, health risks, and societal valuation of these risks. The expected monetary value of the annual health benefits generated by a 10% reduction in U.S. population exposure to MeHg for one year is $860 million; 80% of this is associated with reductions in fatal heart attacks and the remainder with IQ gains. The plausible distribution of the benefits is quite broad with 5th and 95th percentile estimates of approximately $50 million and $3.5 billion, respectively. The largest source of uncertainty is whether epidemiological associations between MeHg exposure and fatal heart attacks reflect causality. The next largest sources of uncertainty concern the slope of the relationship between maternal MeHg exposure and reduced intelligence among children and whether this relationship exhibits a threshold. Our analysis suggests that the possible causal relationship between MeHg exposure and fatal heart attacks should be better characterized, using additional epidemiological studies and formally elicited expert judgment. © 2010 American Chemical Society.


Das Chagas Moura M.,Center for Risk Analysis | Droguett E.L.,Center for Risk Analysis | Firmino P.R.A.,Federal University of Cariri | Ferreira R.J.,Instituto Federal Of Educacao
Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability | Year: 2014

This article develops a model for dependent and imperfect condition-based preventive and corrective maintenance actions. The approach is based on the combination of the intensity proportional repair alert, a competing risks-based model and the generalized renewal process. Typically, intensity proportional repair alert can identify either how preventive actions may modify the distribution of the time between critical failures or how corrective events may change the frequency of preventive maintenances, but this method fails to analyze the effectiveness of the maintenance actions because they are treated as being perfect. On the other hand, generalized renewal process is able to capture the quality of maintenance, classifying it as perfect, minimal or imperfect depending on the value of a rejuvenation parameter. However, generalized renewal process cannot distinguish how different types of maintenance influence each other as intensity proportional repair alert does. Therefore, the intensity proportional repair alert-generalized renewal process hybrid approach is proposed here to fill this gap. This article also develops the maximum likelihood estimators for the proposed model as well as a Monte Carlo-based algorithm to estimate the expected number of preventive and corrective maintenances over time. The proposed model is validated through two example applications for which the intensity proportional repair alert-generalized renewal process model results show close agreement with the failure datasets. © IMechE 2014.


Mandel A.,Tel Aviv University | Stern E.,Center for Risk Analysis | Ullmann A.,Tel Aviv University | Brauner N.,Tel Aviv University
Atmospheric Environment | Year: 2015

An approach is suggested for the estimation of air borne critical particle diameter that determines the dominant removal mechanism from atmospheric dispersion of plumes for six main Pasquill-Gifford meteorological stability conditions. A methodology was developed to apply in rural regions since relevant meteorological input data have been developed mainly for such areas. Our critical diameter methodology refines the commonly accepted "50 micron diameter", considered as a border value above which gravitational settling is dominant and below which, turbulent dispersion is expected to prevail. The interrelationships of particle release heights and downwind deposition distances (for various stability conditions) as well as particle sizes and densities are implemented in the turbulent dispersion and gravitational settling estimations, in order to determine the dominant mechanism for particles reaching the ground following their releases from various heights. © 2015 Elsevier Ltd.

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