Willingness to Pay for Health Protection: Inadequate Sensitivity to Probability?

Efficient investments in health protection require valid estimates of the public's willingness to forgo consumption for diminished probabilities of death, injury, and disease. Stated valuations of risk reduction are not valid measures of economic preference if the valuations are insensitive to probability variation. This article reviews the existing literature on CV studies of reductions in health risk and finds that most studies are poorly designed to assess the sensitivity of stated valuations to changes in risk magnitude. Replication of a recent study published in this journal by Johannesson et al. (1997) demonstrates how serious the problem of insensitivity can be, even for a study that reports plausible results. New empirical results are presented from telephone surveys designed to provide internal and external tests of how WTP responds to size of risk reduction. The effect of variations in instrument design on estimated sensitivity to magnitude is examined. Overall, estimated WTP for risk reduction is inadequately sensitive to the difference in probability, that is, the magnitude of the difference in WTP for different reductions in risk is typically smaller than suggested by standard economic theory. Additional research to improve methods for communicating changes in risk is needed, and future studies of stated WTP to reduce risk should include rigorous validity checks.     

Valuing fatal risks to children and adults: Effects of disease,latency, and risk aversion

We examine heterogeneity of willingness to pay (WTP) to reduce risks of fatal disease and trauma to adults and children. Using a stated-preference survey fielded to a large, nationally representative internet panel, we find that WTP to reduce fatal-disease risks (caused by consuming pesticide residues on foods) are similar for several types of cancer and non-cancer diseases and similar to WTP to reduce motor-vehicle crashes. WTP to reduce risk to one’s child is uniformly larger than to reduce risk to another adult or to oneself. Estimated values per statistical life are $6–10 million for adults and $6–10 million for adults and 12–15 million for children.     

Risk Perceptions and Value of a Statistical Life for Air Pollution and Traffic Accidents: Evidence from Bangkok,Thailand

This paper presents results of two contingent valuation surveys conducted in Bangkok measuring individuals’ willingness to pay (WTP) to reduce mortality risk arising from two risk contexts: air pollution traffic accidents Results from the risk perception survey disclose that respondents view the two risks differently. WTP to reduce air pollution risk is influenced by degrees of dread, severity, controllability and personal exposure, while WTP to reduce traffic accident risk is influenced by perceived immediate occurrence. Nevertheless, the value of a statistical life (VSL) for both air pollution and traffic accidents are comparable (US$0.74 to $1.32 million and US$0.87 to $1.48 million, respectively). This indicates that the risk perception factor alone has little impact on the VSL, a finding similar to previous studies using program choice indifferences.JEL Classification: I18, D61, J17, J28     

Scope insensitivity in health risk reduction studies: A comparison of choice experiments and the contingent valuation method for valuing safer food

Scope insensitivity and embedding are fundamental concerns in contingent valuation studies for health risk reductions. Recently, choice experiments have increasingly been used to obtain contingent willingness to pay (WTP) estimates. We juxtapose the WTP estimates of a choice experiment (CE) to those of the contingent valuation method (CVM) for different health risk reductions and compare them in the extent of scope insensitivity and embedding. WTP using CVM is scope sensitive for single health risks, but embedding is observed for multiple disease risks. In contrast, WTP based on the CE is highly scope sensitive and convex in risk reduction levels.

Willingness to pay for mortality risk reductions: Does latency matter?

Using results from two contingent valuation surveys conducted in Canada and the U.S., we explore the effect of a latency period on willingness to pay (WTP) for reduced mortality risk using a structural model. We find that delaying the time at which the risk reduction occurs by 10 to 30 years reduces WTP by more than 60% for respondents in both samples aged 40 to 60 years. The implicit discount rates are equal to 3.0–8.6% for Canada and 1.3–5.6% for the U.S. JEL Classification Q51 · Q58 The findings, interpretations and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the USEPA or of the World Bank, its Executive Directors or the countries they represent.     

Effects of Disease Type and Latency on the Value of Mortality Risk

We evaluate the effects of disease type and latency on willingness to pay (WTP) to reduce environmental risks of chronic, degenerative disease. Using contingent-valuation data collected from approximately 1,200 respondents in Taiwan, we find that WTP declines with latency between exposure to environmental contaminants and manifestation of any resulting disease, at a 1.5 percent annual rate for a 20 year latency period. WTP to reduce the risk of cancer is estimated to be about one-third larger than WTP to reduce risk of a similar chronic, degenerative disease. The value of risk reduction also depends on the affected organ, environmental pathway, or payment mechanism: estimated WTP to reduce the risk of lung disease due to industrial air pollution is twice as large as WTP to reduce the risk of liver disease due to contaminated drinking water.     

Valuing Mortality-Risk Reduction: Using Visual Aids to Improve the Validity of Contingent Valuation

We investigate the validity of contingent valuation (CV) estimates of the value per statistical life (VSL). We test for sensitivity of estimated willingness to pay (WTP) to the magnitude of mortality-risk reduction and for the theoretically predicted proportionality of WTP to risk reduction using alternative visual aids to communicate risk. We find that WTP is sensitive to the magnitude of risk reduction for independent subsamples of respondents presented with each of three alternative visual aids, but not for the subsample presented with no visual aid. Estimated WTP is consistent with proportionality to risk reduction for the subsamples presented with a logarithmic scale or an array of 25,000 dots, but not for the subsample receiving a linear scale. These results suggest that CV can provide valid estimates of WTP for mortality-risk reduction if appropriate methods are used to communicate the risk change to respondents.     

Reference-dependent valuations of risk: Why willingness-to-accept exceeds willingness-to-pay

The gap between willingness-to-pay (WTP) and willingness-to-accept (WTA) benefit values typifies situations in which reference points—and direction of movement from reference points—are consequential. Why WTA-WTP discrepancies arise is not well understood. We generalize models of reference dependence to identify separate reference dependence effects for increases and decreases in environmental health risk probabilities, for increases and decreases in costs, and reference dependence effects embodying the interaction of two changes. We estimate separate reference dependence effects for the four possible cost and health risk change combinations using data from our choice-based experiment for a nationally representative sample of 4,745 households. The WTA-WTP gap is due largely to the reference dependence effects related to costs. Standard models of reference dependence are not consistent with the results, as there is an interactive effect. Estimated income effects are under a penny and thus cannot account for higher values of WTA relative to WTP.     

An Experimental Investigation of the Disparity Between WTA and WTP for Lotteries

In this paper we experimentally investigate the disparity between willingness-to-accept (WTA) and willingness-to-pay (WTP) for risky lotteries. The direction of the income effect is reversed by endowing subjects with the highest price of a lottery when asking the WTP question. Our results show that the income effect is too small to be the only source of the disparity. Since the disparity concentrates on a subsample of subjects, parametric and nonparametric tests of the WTA-WTP ratio may lead to contradictory results. The disparity is significantly reduced when background risk is introduced. That is, putting subjects always into a risky position could improve the contingent valuation method, which is often concerned with the assessment of risky situations such as health risks, automobile safety, etc.      

Willingness to Pay for Risk Reduction and Risk Aversion without the Expected Utility Assumption

By means of minimal assumptions on the individual preferences, I show that the Willingness To Pay (WTP) for both a FSD and SSD reduction of risk is the sum of a mean effect, a pure risk effect and a wealth effect. As a result, the WTP of a risk-averse decision maker may be lower than the WTP of a risk-neutral one, for a large class of individual preferences’ representation and a large class of risks.     

Admissible utility functions for health, longevity, and wealth: integrating monetary and life-year measures

The value of reducing health and mortality risks is often measured using value per statistical life (VSL) or one of several life-year measures (e.g., life years, quality-adjusted life years, disability-adjusted life years). I derive the utility function that is admissible when preferences for health and longevity, conditional on wealth, are consistent with any life-year measure (LYM) and examine the implications for marginal willingness to pay (WTP) for increases in health, longevity, and current-period survival probability. I conclude that marginal WTP for any LYM is decreasing and that VSL is increasing in the LYM. These results imply that cost-effectiveness analysis using a fixed monetary value per LYM is not consistent with economic welfare theory and that the benefit of a health improvement cannot be calculated by multiplying the change in a LYM by a constant.     

Elicitation of health values from mortality risk reduction

There are concerns regarding uncertainty about the accuracy of applying available empirical willingness-to-pay (WTP) estimates for reducing accidental deaths to value changes in risks of pollution-related deaths. In this study, we develop a theoretical model on defining WTP, and its determinants, and derive WTP estimates for changes in pollution-related mortality risks with varying morbidity and timing attributes. A survey is designed and conducted with 100 subjects. Each subject was to complete five choice sets and provided a range of implicit values of statistical life (VSL). The choices are estimated using the logit procedure. And, using the results of estimated multinomial logit model, the VSL is estimated to about $6.2 million.     

Contextualising the ‘Crisis in Aged Care’ in Australia : A Demographic Perspective

Australia's ‘old‐old’ population is growing even faster than the total aged population and despite improved incomes, living conditions, health risk behaviours and health care this will result in a concomitant increase in the numbers of older people with disabilities. This paper examines ABS 2003 survey data on the incidence of disability among older Australians and their need for, and utilisation of, formal and informal care. It uses this as a basis for projecting the incidence of disability among older Australians and the need for informal and formal care up to 2031. These indicate there is a major challenge since the aged care workforce has grown only slowly in Australia and is concentrated in the older working ages presaging a loss of workers through retirement. There needs to be a significant effort put into attracting workers to both the skilled and unskilled parts of the aged care industry.     

Determinants of the demand for health screening in Malaysia: The case of the aged population

The increase in the prevalence of heart disease has become a serious public health issue. Hypercholesterolemia and hypertension are two main modifiable health risk factors for heart disease. In a fast ageing society, proper preventive measures should be adopted, particularly to achieve healthy aging. The objective of the present study is to examine the factors affecting the use of two health tests, namely blood cholesterol and blood pressure screenings among adults aged 60 years and above in Malaysia. Nationally representative data collected through the National Health and Morbidity Survey 2011 (NHMS, 2011) by the Ministry of Health, Malaysia were analysed. The survey used a two-stage stratified sampling method. Enumeration Blocks were selected in the first stage, while the second stage involved selection of Living Quarters. The proportions of those not using the blood cholesterol (45.4%) and blood pressure (30.8%) tests are alarmingly high. A bivariate probit model is applied to examine the determinants of the use of these two health screening tests. The results show that education, ethnicity, location of residence, employment status, health insurance and smoking significantly affect the decision of the aged population to undergo these tests. Key findings are, first, time is a more dominant factor than income in determining health screening behaviour among the aged population. Second, being covered by insurance increases the propensity to undergo health screening. Third, smokers have a lower likelihood of screening than non-smokers. The findings suggest that intervention programmes should be targeted at the less-educated, employed individuals, individuals not covered by health insurance and smokers.     

The Benefits of Reducing Gun Violence: Evidence from Contingent-Valuation Survey Data

This article presents an estimate of the benefits of reducing crime using the contingent-valuation (CV) method. We focus on gun violence, a crime of growing policy concern in America. Our data come from a national survey in which we ask respondents referendum-type questions that elicit their willingness-to-pay (WTP) to reduce gun violence by 30%. We estimate that the public's WTP to reduce gun assaults by 30% equals $24.5 billion, or around $1.2 million per injury. Our estimate implies a statistical value of life that is quite consistent with those derived from other methods.     

The value of private safety versus the value of public safety

In this study, one group of respondents is offered to purchase a safety device to be installed in their cars, while another group is offered a public safety program (improved road quality) which results in the same size risk reduction. In terms of the value of a statistical life, our results are very reasonable. However, the WTP for the private safety device ishigher than the WTP for the public safety measure. Drawing on a model developed by Jones-Lee (1991), we show that some types of altruists may, but need not, be willing to pay more for a private risk reduction than for a uniform risk reduction of the same magnitude. Still, our empirical results are surprising, and further empirical research seems warranted.     

Imprecise preferences and the WTP-WTA disparity

This article reports the results of a study designed to elicit willingness to pay (WTP) and willingness to accept (WTA) values for changes in the risk of nonfatal road injuries. We examine the possibility that individuals' preferences over combinations of wealth, risk, and safety are imprecise, and that this imprecision might result in the observed disparity between WTP and WTA measures of value. The results confirm that individuals' preferences for safety are significantly imprecise, but that this alone is insufficient to explain more than part of the disparity. Indeed, respondents' estimates of the minimum that they would be prepared to accept for a risk increase frequently exceed the maximum that they would be prepared to pay for an equivalent risk reduction.     

The Effect of Environmental Disclosure Requirements on Willingness to Pay for Residential Properties in Borderlands Community*

Objective. This study examines the effect of environmental information disclosure requirements on future real estate transactions. The setting involves pollution from a concrete products and quarrying site near a largely Hispanic, residential community. Methods. The survey‐based contingent valuation (CV) method is used to test the hypothesis that a split‐sample treatment for an information disclosure requirement with a potentially negative affective quality will reduce the willingness to pay (WTP) of potential buyers for a typical property. Results. Results indicate that the information disclosure treatment reduces WTP, and that this effect is significantly exacerbated when the surveys are conducted in Spanish. Conclusions. In addition to identifying significant reductions in the WTP of potential home buyers, our findings demonstrate the importance of cultural and regional considerations for how information disclosure requirements are conducted in real estate transactions. Future CV studies should also consider Spanish‐language options in applications involving significant Hispanic populations.     

Reference points,loss aversion,and contingent values for auto safety

This article is concerned with the possible role of reference points and loss aversion (as suggested by prospect theory) in subjects' judgments about the value of increments and decrements in automobile safety. The contingent valuation method is employed in two experiments, both of which consider subjects' willingness-to-pay (WTP) for increased safety and compensation demanded (CD) for decreased safety in hypothetical new vehicle purchases. The results establish that disparities exist in subjects' WTP and CD values for the same increment of auto safety, even for a close-to-market context such as hypothetical new vehicle purchases. The results also indicate that evaluations can be manipulated by changing the perception of the reference point: losses can be recast as forgone gains and forgone gains as losses, altering (or even eliminating) differences between WTP and CD values.I would like to thank Mark Kamlet, Greg Fischer, and Granger Morgan for advice and help in structuring the research for the first experiment; Paul Slovic and Jack Knetsch for suggestions regarding the structure and content of the second experiment; Robin Gregory and two anonymous referees for insightful comments on earlier drafts; and the subjects who provided their time in the two experiments. Michael McNickle provided able research assistance for the second experiment. The survey for the first experiment was partially supported by the Program for Technology and Society at Carnegie Mellon University, with funds from the Andrew W. Mellon Foundation.     

Does the WTA/WTP ratio diminish as the severity of a health complaint is reduced? Testing for smoothness of the underlying utility of wealth function

The aim of the study reported in this paper is to test the hypothesis that individual utility of wealth functions may violate the assumption of smoothness that underpins the standard analysis of the Value of Statistical Life (VSL) and safety. In order to do so we examine the way in which the Willingness to Accept/Willingness to Pay (WTA/WTP) ratio varies as the severity of a health complaint is reduced. We find that as the severity of the health effect is reduced, the WTA/WTP ratio converges across the sample and tends to a level that does not significantly exceed unity. While we acknowledge that this does not constitute conclusive evidence of smoothness, it does suggest that the case in favour of the assumption that individual utility of wealth functions tend to display a kink at the current level of wealth is less than wholly persuasive.