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In response to an emerging pandemic, there is urgent need for information regarding individual evaluation of risk and preferences toward mitigation strategies such as vaccinations. However, with social distancing policies and financial stress during an outbreak, traditional robust survey methodologies of face‐to‐face, probabilistic sampling, may not be feasible to deploy quickly, especially in developing countries. We recommend a protocol that calls for a sensitive survey design, acceptance of a web‐based approach and adjustments for uncertainty of respondents, to deliver urgently needed information to policymakers as the public health crisis unfolds, rather than in its aftermath. This information is critical to tailor comprehensive vaccination campaigns that reach critical immunity thresholds. We apply our recommendations in a regional study of 16 Latin American countries in the month following index cases of COVID‐19. We use a split‐sample, contingent valuation approach to evaluate the effects of cost, duration of immunity and effectiveness of the vaccine. Our results show that cost and duration of immunity are significant factors in the decision to vaccinate, while the degree of effectiveness is insignificant, unless the vaccine is 100% effective. Income as well as perceived risk and severity of the virus are important determinants also.

Many aspects of asthma-in particular the relationship between beliefs, averting behaviors, and symptoms-are not directly observable from market data. An approach that combines observable market data with nonmarket valuation to gather data on unobservable aspects of the illness can improve efforts to quantify the burden of asthma if it accounts for the endogeneity in the system. Such approaches are used in the valuation of recreation but have not been widely used to value the burden of a chronic illness. We estimate parents' willingness to pay (WTP) to reduce their child's asthma symptoms using a three-equation model that combines revealed preference, contingent valuation, and burden of asthma, increasing the efficiency of estimation and correcting for endogeneity. WTP for a device that reduces a child's asthma symptoms by 50% is $125/month (s.d. $20). Parents' valuations are driven by beliefs about asthma and by their degree of worry about asthma between episodes. There is a nonlinear relationship between the number of days with symptoms and WTP per symptom day. The experience of living with asthma affects families' responses to a contingent valuation scenario, because it influences willingness to spend money to manage the illness and their subjective perceptions and beliefs about the illness itself.

Despite the importance of including children's preferences in the valuation of their own health benefits, no study has investigated the ability of children to understand willingness-to-pay (WTP) questions. Using a contingent valuation method, we elicit children's and parents' WTP to reduce children's risk of an asthma attack. Our results suggest that children are able to understand and value their own health risk reductions, and their ability to do so improves with age. Child age was found to be inversely related to parents' and children's WTP. The results also suggest that non-paternalistic altruism is predictive of children's WTP. For parents, care for their own health was found to be inversely related with their WTP for children's risk reductions. Comparison of parents' and children's WTP suggests that parents are willing to sacrifice for their child's health risk reduction an amount that is approximately twice that of their children. The analysis of matched pairs of parents and children suggest that there are within-household similarities as the child's WTP is positively related to parents' WTP.

We evaluate the introduction of various forms of antihypertensive treatments in France with a distribution-sensitive cost-benefit analysis. Compared to traditional cost-benefit analysis, we implement distributional weighting based on equivalent incomes, a new concept of individual well-being that does respect individual preferences but is not subjectively welfarist. Individual preferences are estimated on the basis of a contingent valuation question, introduced into a representative survey of the French population. Compared to traditional cost-effectiveness analysis in health technology assessment, we show that it is feasible to go beyond a narrow evaluation of health outcomes while still fully exploiting the sophistication of medical information. Sensitivity analysis illustrates the relevancy of this richer welfare framework, the importance of the distinction between an ex ante and an ex post approach, and the need to consider distributional effects in a broader institutional setting.

The appropriate thresholds for decisions on the cost-effectiveness of medical interventions remain controversial, especially in 'end-of-life' situations. Evidence of the values placed on different types of health gain by the general public is limited. Across nine European countries, 17 657 people were presented with different hypothetical health scenarios each involving a gain of one quality adjusted life year (QALY) and asked about their willingness to pay (WTP) for that gain. The questions included quality of life (QoL) enhancing and life extending health gains, and a scenario where respondents faced imminent, premature death. The mean WTP values for a one-QALY gain composed of QoL improvements were modest (PPP$11 000). When comparing QALY gains obtained in the near future, the valuation of life extension exceeded the valuation of QoL enhancing gains (mean WTP PPP$19 000 for a scenario in which a coma is avoided). The mean WTP values were higher still when respondents faced imminent, premature death (PPP$29 000). Evidence from the largest survey on the value of health gains by the general public indicated a higher value for life extending gains compared with QoL enhancing gains. A further modest premium may be indicated for life extension when facing imminent, premature death. Copyright © 2013 John Wiley & Sons, Ltd.

Willingness to pay (WTP) values derived from contingent valuation surveys are prone to a number of biases. Range bias occurs when the range of money values presented to respondents in a payment card affects their stated WTP values. This paper reports the results of an exploratory study whose aim was to investigate whether the effects of range bias can be reduced through the use of an alternative to the standard payment card method, namely, a random card sort method. The results suggest that the random card sort method is prone to range bias but that this bias may be mitigated by restricting the analysis to the WTP values of those respondents who indicate they are 'definitely sure' they would pay their stated WTP.

SUMMARY This paper analyzes the impact of external sources of information, conveyed by the frequency of risky events that vary across time, on the individual willingness to pay (WTP) for a reduction of mortality risk. We collected data from a contingent valuation (CV) exercise conducted in two waves (fall and winter) to examine whether individual WTP varied across periods that differed in the predominance of fatal accidents. Risk valuations were based on fatal snow avalanche accidents, that is, a type of risk with seasonal differences in occurrence. We found slightly lower but statistically significant mean WTP figures in the winter than in the fall sample because of time-varying individual risk attitudes and, therefore, recommend controlling for these factors in risk assessment CV surveys. Copyright © 2013 John Wiley & Sons, Ltd.

In this study, respondents were randomly allocated to three variants of the payment card format and an open-ended format in order to test for convergent validity. The aim was to test whether preferences (as measured by willingness to pay additional tax) would be affected by framing the willingness-to-pay question differently. Results demonstrated that valuations were highly sensitive to whether respondents were asked to express their maximum willingness to pay per month or per year. Another important finding is that the introduction of a binary response filter prior to the payment card follow-up tends to eliminate the positive aspects of introducing a payment card and produces response patterns that are much in line with those of the open-ended contingent valuation format. However, although a filter will impact on the distribution of willingness-to-pay bids and on the rate of zero and protest bids, the overall impact on the welfare estimate is minor. The outcomes of this study indicate that valuations in the stated preference literature may be, at least in part, a function of the instrument designed to obtain the valuations.

Interpreting the outcomes of cost utility analyses requires an appropriately defined threshold for costs per quality-adjusted life year (QALY). A common view is that the threshold should represent the (consumption) value a society attaches to a QALY. So far, individual valuations of personal health gains have mainly been studied rather than potentially relevant social values. In this study, we present the first direct empirical estimates of the willingness to pay for a QALY from a societal perspective. We used the contingent valuation approach, valuing QALYs under uncertainty and correcting for probability weighting. The estimates obtained in a representative sample of the Dutch population (n = 1004) range from €52,000 to €83,000, depending on the specification of the societal perspective. The scale sensitivity was weak, however.

Cervical cancer is one of the leading causes of cancer deaths in Taiwan. To investigate the disease cost and then raise awareness of the importance of screening for cervical cancer and promote early detection, this paper employs contingent valuation and willingness to pay (WTP) method to study how health-related quality of life, disease severity, and after-treatment disease status affect patients' WTP for a complete remission of the disease. The inclusive criteria for the study were primary case outpatients at least 3 months after they had received therapy at the time of our study period. Face-to-face interviews were conducted for the retrospective format of the survey. The result of the study indicates a lifetime WTP of $US21 221.96 for Taiwanese cervical cancer patients, which is significantly higher than the cost of screening for early detection. Disease stages do not show a consistent pattern in influencing WTP, but patients with surgery are willing to pay a significantly higher amount for a complete remission from the disease than patients without. In addition, mental health, positive attitudes toward life, and quality of life also are key factors that influence WTP.

The main purpose of the present study was to test for outcome scope insensitivity. Respondents were initially asked to value one of two severe health states by way of a time-trade-off (TTO) exercise. Subsequent to the TTO exercise all respondents were asked to value an intervention, which offered a reduction in risk of falling into the health state they had evaluated. All respondents were subsequent to this initial CV exercise asked to value the same risk reduction, but in this case the outcome was death. Although our study passes the internal scope test, there is not a high degree of sensitivity to outcome. As many as 68% of respondents stated an identical maximum WTP in first and second CV valuation exercise implying that they value the interventions equally despite the fact that the health state presented in the initial CV question was deemed far better than death according to the TTO responses given by the same respondents. In contrast, the external scope test (comparison of response to initial CV across study arms) fared much better.

While informal care is a significant part of non-market economic activity, its value is rarely acknowledged, perhaps reflecting a lack of market data. Traditional methods to value such care include opportunity and replacement cost. This study is the first to employ the discrete choice experiment methodology to value informal care tasks. A monetary value is estimated for three tasks (personal care, supervising and household tasks). The relationship between time spent on formal and informal care is also modelled and preference heterogeneity investigated using the Latent Class Model. Complementarity between supervising tasks and formal care is observed. Monetary compensation is important, with willingness to accept per hour values ranging from £0.38 to £0.83 for personal care, £0.75 for supervising and £0.31 to £0.6 for household tasks. Heterogeneity in preferences is observed, with monetary compensation being important for younger people, but insignificant for older individuals. Such heterogeneity is important at the policy level. Values are lower than those generated by opportunity cost and replacement cost methods, perhaps because of the limited ability of revealed preference methods to capture broader aspect of utility. Differences with contingent valuation methods are also observed, suggesting future research should investigate the external validity of the different methods.

Including informal care in economic evaluations is increasingly advocated but problematic. We investigated three well-known concerns regarding contingent valuation (CV): (1) the item non-response of CV values, (2) the sensitivity of CV values to the individual circumstances of caring, and (3) the choice of valuation method by comparing willingness-to-pay (WTP) and willingness-to-accept (WTA) values for a hypothetical marginal change in hours of informal care currently provided. The study sample consisted of 1453 caregivers and 787 care recipients. Of the caregivers, 603 caregivers (41.5%) provided both WTP and WTA values, 983 (67.7%) provided at least one. Determinants of non-response were dependent on the valuation method; primary determinants were education and satisfaction with amount of informal care provided. Caregivers' mean WTP (WTA) for reducing (increasing) informal care by 1 h was €9.13 (10.52). Care recipients' mean WTA (WTP) for reducing (increasing) informal care by 1 h was €8.88 (€6.85). Values were associated with a variety of characteristics of the caregiving situation; explanatory variables differed between WTP and WTA valuations. The differences between WTP and WTA valuations were small. Based on sensitivity CV appears to be a useful method to value informal care for use in economic evalations, non-response, however, remains a matter of concern. Copyright © 2009 John Wiley & Sons, Ltd.

This study presents the first comparison of willingness to pay estimates derived from the payment card (PC) contingent valuation and discrete choice experiment (DCE) methods. A within-sample experiment was used to elicit women's preferences for Chlamydia screening. The willingness to pay estimate derived from the DCE was larger than that derived from the PC. To investigate why the willingness to pay estimates were different, a range of validity tests were conducted. Both methods produced theoretically valid results, and there was no difference in the reported difficulty of completing the tasks. Evidence of a prominence effect was found in the PC responses. Responses to the DCE satisfied tests of non-satiation. Responses to both methods were compared with revealed preference data. There were significant differences between stated screening intention in both methods and actual screening uptake. Future work should address the external validity of stated preference methods.

Reduced crime provides a key benefit associated with substance abuse treatment (SAT). Armed robbery is an especially costly and frequent crime committed by some drug-involved offenders. Many studies employ valuation methods that understate the true costs of robbery, and thus the true social benefits of SAT-related robbery reduction. At the same time, regression to the mean and self-report bias may lead pre-post comparisons to overstate crime reductions associated with SAT. Using 1992-1997 data from the National Treatment Improvement Evaluation Study (NTIES), we examined pre-post differences in self-reported robbery among clients in five residential and outpatient SAT modalities. Fixed-effect negative binomial regression was used to examine incidence rate reductions (IRR) in armed robbery. Published data on willingness to pay to avoid robbery were used to determine the social valuation of these effects. Differences in IRR across SAT modalities were explored to bound potential biases.All SAT modalities were associated with large and statistically significant reductions in robbery. The average number of self-reported robberies declined from 0.83/client/year pre-entry to 0.12/client/year following SAT (p

In a recent article in this journal, Smith offers additional evidence to support his claim that the test–retest reliability of willingness to pay measures increases along with willingness to pay because people take more time to consider their answers for the more highly valued (and therefore more ‘expensive’) goods. Unfortunately, by repeating a common misconception about what reliability actually measures, he overlooks an alternative explanation for the relationship he observed; namely, that subject variation increases with willingness to pay and that it is this, rather than any reduction in measurement error, that explains his findings. We show that 75% of the increase in reliability comes from increases in subject variation (that is different views about the value of good health), and that the relationship between measurement error and willingness to pay is not as simple as Smith suggests. However, our critique of Smith's paper should not be construed as criticism of the ideas being explored. We need to better understand the responses people give to contingent valuation exercises. Such understanding has to be based on a better appreciation of what reliability is and on more robust testing of alternative hypotheses. Copyright © 2007 John Wiley & Sons, Ltd.

This paper estimates the monetary value of providing informal care by means of a well-being valuation method. This is done by assessing the compensating variation necessary to maintain the same level of well-being after an informal caregiver provides an extra hour of informal care. The informal caregiver's well-being is proxied by the answer to two subjective well-being questions that were posed in a questionnaire answered by 865 Dutch informal caregivers between the end of 2001 and the beginning of 2002. In the econometric analysis, a distinction is made between the care recipients who are and the ones who are not a family member of the informal caregiver. The results indicate that an extra hour of informal care is worth about 9 or 10 Euros. This equals 8 or 9 Euros if the care recipient is a family member and about 7 or 9 Euros if not. When applying the contingent valuation method to the same sample, the value obtained was 10.52 Euros per hour. This paper concludes that the well-being valuation method is a useful complement to the more traditional valuation methods in the health economics literature in general and more particularly for the economic valuation of informal care: it includes all costs and effects associated with providing care from the perspective of the informal caregiver, it is relatively cheap to implement, and it offers an additional possibility to determine the convergent validity of the different monetary valuation methods. Copyright © 2007 John Wiley & Sons, Ltd.

A general population sample of Australian respondents completed a contingent valuation (CV) survey that asked them to value six scenarios. These varied according to whether the scenario was seeking to elicit: (i) use value; (ii) externality value; (iii) option value; or (iv) a combination. Results indicate that use plus externality and/or option value was significantly greater than use value alone. As CV studies in health (care) overwhelmingly focus on use value alone - often implicitly through study design rather than explicitly - this raises the possibility of mis-specification in CV research in health (care). The implications for CV in health (care) are considered. Copyright (c) 2006 John Wiley & Sons, Ltd.

A contingent valuation was performed based on cross-sectional web-based interviews of individuals aged 16-82 years of age presenting a scenario of influenza pandemic. The mean WTP for a course of Tamiflu was NOK 1034 (median NOK 250). Anxious individuals perceived the pandemic mortality risk to be higher than others, but also perceived the benefit of Tamiflu as greater. They also expressed a higher WTP for Tamiflu, but the implied VOSL was less than for other respondents. The results suggest that fear and anxiety distort decision making under uncertainty and decrease focus on the perceived risk reduction.

We present data of a contingent valuation survey, testing the effect of evaluation mode on the monetary valuation of preventing road accidents. Half of the interviewees was asked to state their willingness to pay (WTP) to reduce the risk of having only 1 type of injury (separate evaluation, SE), and the other half of the sample was asked to state their WTP for 4 types of injuries evaluated simultaneously (joint evaluation, JE). In the SE group, we observed lack of sensitivity to scope while in the JE group WTP increased with the severity of the injury prevented. However, WTP values in this group were subject to context effects. Our results suggest that the traditional explanation of the disparity between SE and JE, namely, the so-called "evaluability," does not apply here. The paper presents new explanations based on the role of preference imprecision.

This paper describes an experiment to test the construct validity of contingent valuation, by eliciting women's valuations for the NHS cervical cancer screening programme. It is known that, owing to low levels of knowledge of cancer and screening in the general population, women both over-estimate the risk of disease and the efficacy of screening. The study is constructed as a randomised experiment, in which one group is provided with accurate information about cervical cancer screening, whilst the other is not. The first hypothesis supporting construct validity, that controls who perceive greater benefits from screening will offer higher valuations, is substantiated. Both groups are then provided with objective information on an improvement to the screening programme, and are asked to value the improvement as an increment to their original valuations. The second hypothesis supporting construct validity, that controls who perceive the benefits of the programme to be high already will offer lower incremental valuations, is also substantiated.

The use of discrete-choice contingent valuation (CV) to elicit individuals' preference, expressed as maximum willingness-to-pay (WTP), although primarily developed in environmental economics, has been popular in the economic evaluation of health and healthcare. However, a concern with this method is the potential for 'over-estimating' WTP values due to the presence of response acquiescence, or 'yea-saying' bias. Based on a CV survey conducted to estimate physicians' valuation of clinic computerization, the extent of such bias was estimated from a within-sample open-ended valuation question following the respondents' discrete choice response. Analysis of this data suggests that not only was response acquiescence an issue, but also that the parametric estimation of mean and median WTP, the most common approach to estimating WTP from discrete-choice data, would potentially magnify such bias (to various degrees depending on the distributional assumptions applied). The possible extent of CV design versus analysis in discrete-choice methods therefore warrants further exploration.

A general population sample of 314 Australian respondents were randomly allocated to complete a contingent valuation survey administered by face-to-face or telephone ('phone-mail-phone') interview. Although the telephone interview was quicker to complete, no significant difference was found in values obtained through either method. Within each sub-sample, respondents were also randomly allocated to the three different versions of the payment card (PC) questionnaire format: values listed from high-to-low, values listed from low-to-high and values randomly shuffled. The high-to-low version resulted in significantly higher values than the other versions. Further analyses indicate that the randomly shuffled PC version may produce the most 'valid' values.

Criticism of contingent valuation (CV) stresses warm glow and free-riding as possible causes for biased willingness to pay figures. We present an empirical framework to study the existence of warm glow and free-riding in hypothetical WTP answers based on a CV survey for the measurement of health-related Red Cross services. Both in conventional double-bounded and spike models we do not find indication of warm glow phenomena and free-riding behaviour. The results are very robust and insensitive to the applied payment vehicles. Theoretical objections against CV do not find sufficient empirical support.

This study examined the influences of the interaction between a bid and the respondent's characteristics due to insufficient random assignment of bids on the estimation of willingness to pay (WTP) using data from a discrete-choice question. A contingent valuation survey of 152 examinees undergoing X-ray testing for gastric cancer screening was conducted, and the median and mean WTP for the serum pepsinogen test were estimated using a logistic regression model to which the interaction terms between the bid and the respondent's characteristics, which included gender, age, annual income, frequency of prior use of a gastric cancer screening program, and perceived health, were added. There were remarkable differences in the estimated WTP according to whether the interaction term of annual income, to which the bids had failed to be assigned randomly and which had been positively correlated with the bid, was added in the model. It is suggested that it may be necessary to check if the bids were randomly assigned to the respondent's characteristics and, when correlations with the bid are found, to adjust their interaction effects.

This paper examines the inter-rater and test-retest reliability of willingness to pay (WTP) for insecticide-treated mosquito nets and net re-treatment using the bidding game (BG), binary with follow-up (BWFU) and a novel structured haggling technique (SH). Inter-rater reliability was evaluated by having two sets of interviewers administer questionnaires to 109 (BG), 110 (BWFU) and 103 (SH) randomly selected household heads. Test-retest reliability was investigated by repeating interviews on 146 (BG), 161 (BWFU) and 139 (SH) household heads one month after an initial survey. Data analysis used testing of means, Spearman's correlation and Pearson's correlation coefficient for test of reliability, while non-parametric analysis was used to determine factors causing a variation in WTP. The study was conducted in Southeast Nigeria. Inter-rater reliability coefficients were estimated for the individual's WTP for own nets, WTP for others and WTP for re-treatment. Using WTP for own nets as the best reliability estimate, the coefficients were high at values of 0.77 (C.I. 0.72-0.86), 0.75 (C.I. 0.64-0.81) and 0.74 (C.I. 0.63-0.82) in the BG, BWFU and SH, respectively. In test-retest reliability coefficients, the coefficients for WTP for own nets were low-to-moderate at values of 0.51 (C.I. 0.40-0.62), 0.41 (C.I. 0.28-0.53) and 0.56 (C.I. 0.41-0.65) for the BG, BWFU and SH groups, respectively. Factors such as gender, change in income, unplanned expenditures, stated WTP in first survey, time-to-think, external information, and subjecting respondents to more than one interview explained the lower test-retest reliability coefficients. We conclude that the CVM was reliable in the study area and the question formats had similar levels of reliability. The lower coefficients in the test-retest reliability were due to the influence of factors affecting demand that had changed in the intervening period. Standard formats for determining reliability within CVM should be developed for easy comparison of results from different studies.

This paper reports the results of the application of the contingent valuation method (CVM) to determine a monetary value of informal care. We discuss the current practice in valuing informal care and a theoretical model of the costs and benefits related to the provision of informal care. In addition, we developed a survey in which informal caregivers' willingness to accept (WTA) to provide an additional hour of informal care was elicited. This method is better than normally recommended valuation methods able to capture the heterogeneity and dynamics of informal care. Data were obtained from postal surveys. A total of 153 informal caregivers and 149 care recipients with rheumatoid arthritis returned a completed survey. Informal caregivers reported a mean WTA to provide a hypothetical additional hour of informal care of 9.52 Euro (n=124). Many hypotheses derived from the theoretical model and the literature were supported by the data.CVM is a promising alternative for existing methods like the opportunity cost method and the proxy good method to determine a monetary value of informal care that can be incorporated in the numerator of any economic evaluation.

Objectives: To determine whether the binary with follow-up (BWFU) or open-ended (OPED) contingent valuation question format would yield better valid estimates of altruistic willingness to pay (WTP) and examine the feasibility of using intra-community altruistic contributions to procure insecticide-treated nets (ITNs) for the poor in Nigeria. Methods: Structured questionnaires were used to elicit stated altruistic WTP from a random sub-sample of respondents that had either the OPED or BWFU used to elicit WTP in Southeast Nigeria. One month after the survey the respondents were asked to redeem their WTP pledges. Construct validity was determined using econometric analyses while phi correlation was used to determine criterion validity. Findings: More than 57% of the respondents were hypothetically willing to pay for altruism in both BWFU and OPED groups. Altruistic WTP was positively related to respondents WTP for own nets (p

For cost–benefit analysis, health technologies with multiple effects should be valued in a single scenario by a holistic willingness-to-pay (WTP) measure. Recent studies instead used decomposed scenarios in which respondents report their WTP for each individual effect. Evidence can be found that the sum of such decomposed WTPs overestimates the holistic WTP, i.e. the holistic WTP is sub-additive. This sum of decomposed WTPs can lead to wrong conclusions on the efficiency of health technologies. This is also relevant in decision making about new technologies that are valued separately in different surveys. To date, no utility-theoretical and empirically validated aggregation function for decomposed WTPs exists. Within an expected utility model, this paper identifies as a reason for sub-additivity – beside risk aversion with respect to wealth – a negative influence of better health on the marginal utility of wealth, i.e. marginal utility of wealth is smaller in better health states. Assuming mutual utility independence of health and wealth, a theoretically founded aggregation function covering these two impacts is derived. In a contingent valuation study, 92 patients with diabetes were asked to state their WTP for reductions of the risk of several diabetic complications in decomposed as well as in holistic scenarios. The patients had preferences with a significant negative influence of health on the marginal utility of wealth. Sub-additivity occurred and theoretically founded aggregation could considerably lower the degree of overestimation. These results suggest that the theoretically founded aggregation function might reduce problems of sub-additivity that can be economically relevant. Further empirical testing of the approach is indicated. Copyright © 2003 John Wiley & Sons, Ltd.

The health risk of smoking is valued using the contingent valuation method, applied to a Swedish sample of smokers. The respondents were asked to put a value on newly developed cigarettes with no associated health risks. The average additional willingness to pay for the new cigarettes is estimated to be between 10 and 41 SEK per pack, where the variation is due to statistical method, discounting, and whether the open-ended or closed-ended question format is used. Using medical data on life shortening effects of smoking, the results indicate rather low values put on a lost life-year, compared to most existing estimates based on other methods. This may indicate that smokers do underestimate the health risk of smoking. There is also initial optimism-bias regarding people's own ability to quit smoking at will. However, there are remaining methodological questions and we found little or no sensitivity to scope.

The use of willingness to pay to value the benefits of health care is increasing. Much of this work assumes that health preferences are well formed or ‘complete’ and readily revealed if the right question is asked in the right way. We examined this assumption, seeking evidence in a mixed-methods study that explored the meaning and implications of vague responses to a payment-scale based willingness to pay exercise. One-half of the sample said that their vagueness meant that their maximum willingness to pay was actually greater than the amount that they had previously said it was. Thirty percent agreed that they would probably pay £10 more than a sum that they had previously said they would most definitely not pay, if they found this to be the cost of the vaccine. Interview data supported the view that the payment scale had failed to elicit the maximum willingness to pay and that some participants used the information on cost to help clarify their values, in contrast to the theory underpinning willingness to pay. The results suggest a need to consider values-clarification in health economic evaluations. Copyright © 2002 John Wiley & Sons, Ltd.

Three measures of the value of time - willingness to pay (WTP) for a reduction in travel time, willingness to accept (WTA) a monetary compensation to forgo it, and the wage rate - are evaluated and compared. WTP and WTA were estimated from the two-part regressions of time price, using contingent valuation methods with primary survey data. Systematic differences are found in comparisons of WTP and WTA with the wage rate.

Contingent valuation (CV) has been criticised for being too hypothetical, with expressed values bearing little relation to actual values. The magnitude of this divergence, however, depends upon how realistic and believable the contingent market is. This paper presents an overview of five key aspects in the construction of the contingent market: (i) scenario development and presentation; (ii) payment vehicle; (iii) expression of risk; (iv) time period of valuation; and (v) survey administration. CV studies in health care since 1985, totalling 111, are critically reviewed with respect to these five aspects. It is concluded that CV studies in health care have performed poorly in the construction, specification and presentation of the contingent market, and that there has been little, if any, improvement in this respect over the last 15 years. Suggestions are made concerning why this may be the case, and how the construction of the contingent market may be improved in future.

This paper presents results on the valuation of health risks in the presence of altruism. The contingent valuation method is utilised in a split sample experiment for estimating the private and public values in reducing the risk of flu. Data modelling for the dichotomous choice method follows a Bayesian approach, which accounts for zero responses and is adequate for the comparison of small sample results. The results of the experiment suggest that altruism is a positive component in the value of reducing the probability of flu, which depends positively on the number of days involved, the health status and the personal income of the subject. The marginal value of risk is found to be a decreasing function of the reduction in the probability of becoming ill.

In this study, the convergent validity of the contingent valuation method (CVM) and travel cost method (TCM) is tested by comparing estimates of the willingness to pay (WTP) for improving access to mammographic screening in rural areas of Australia. It is based on a telephone survey of 458 women in 19 towns, in which they were asked about their recent screening behaviour and their WTP to have a mobile screening unit visit their nearest town. After eliminating missing data and other non-usable responses the contingent valuation experiment and travel cost model were based on information from 372 and 319 women, respectively. Estimates of the maximum WTP for the use of mobile screening units were derived using both methods and compared. The highest mean WTP estimated using the TCM was $83.10 (95% C.I. $99.06-$68.53), which is significantly less than the estimate of $148.09 ($131.13-$166.60) using the CVM. This could be due to the CVM estimates also reflecting non-use values such as altruism, or a range of potential biases that are known to affect both methods. Further tests of validity are required in order to gain a greater understanding of the relationship between these two methods of estimating WTP.

The use of day case surgery has increased rapidly as an alternative to inpatient surgery. Little is known, however, about the value of day case surgery to patients. The aim of this paper was to develop a contingent valuation survey to investigate how individuals value the costs of shifting from inpatient to day case surgery based on home care services. Using the willingness to pay (WTP) approach, two kinds of sequential experiments are compared: the maximum likelihood recursion (MLR) method and the C-optimal sequential procedure. The goal of sequential experimentation is to find bid values that provide the maximum possible information about the parameters of the WTP distribution, especially when the sample size is small. The C-optimal sequential procedure is shown to be an improvement, in terms of the statistical precision in small samples, over the MLR method. In addition, the paper presents a double hurdle (DH) approach for modelling the determinants of individuals' WTP. Using data from a contingent valuation survey conducted in 1996 on patients selected from the Day Case Surgery Unit in a hospital in the region of Catalonia, we argue that participation in the market offered and the level of consumption, that is, people's WTP, should be treated as individual choices. The results show that income and sex are related to WTP. Also, in this study, a clear presence of starting-point bias, introduced by the bid offered, was found. It is concluded that the WTP technique is potentially useful in evaluating health care programmes, although it is important to note that the criteria used to find an optimal design (in our model to minimize the asymptotic variance of the estimator used) may be restrictive from an economic point of view.

We use the contingent valuation (CV) method to estimate mothers' willingness to pay (WTP) to protect themselves and their children from suffering a minor illness-a cold-in Taiwan. WTP is specified as a hedonic function of the duration and severity of the cold (measured alternatively by symptoms experienced and the Quality of Well-Being (QWB) index) and of respondents' socioeconomic characteristics. The average mother is willing to pay more to protect her child than herself from suffering a cold. Median WTP to avoid the average mother's and child's colds are US$37 and US$57, respectively. Adjusting for the greater duration and severity of the average mother's cold suggests that WTP to prevent comparable illnesses is approximately twice as large for the child as for the mother. We also find that mother's WTP is about 20% greater to prevent a son's than a daughter's illness.

Purpose: The contingent valuation method (CVM) is a survey-based approach for eliciting consumer's monetary valuations for programme benefits for use in cost-benefit analysis (CBA). We used the conceptual framework of O'Brien and Gafni (1996) to classify and critically appraise health care CVM studies. Methods: Search of computerized health care and economic citation databases (e.g. MEDLINE, ECONLIT) and manual search for papers published between 1984–1996 reporting primary data valuing health programme benefits in monetary units by CVM using willingness-to-pay (WTP) or accept (WTA). We classified studies using both empirical (i.e. who was surveyed and how) and conceptual criteria (i.e. which measure of consumer utility was measured and why). Results: 48 CVM studies were retrieved; the majority (42) undertook money valuation in the context of cost benefit analysis (CBA), with the remainder being pricing/demand studies. Among the 42 CBA studies, the consumer utility being measured (i.e. compensating (CV) vs. equivalent variation (EV) was explicitly stated in only three (7%) studies). WTP was measured in 95% of studies and WTA in 5%. By cross-tabulation, 42 (91%) studies were designed as WTP/CV, two (4%) were WTP/EV, two (4%) were WTA/CV and no studies used WTA/EV. Most studies were administered by mail (52%) with 38% being in-person interviews. Value elicitation techniques included open-ended questions (38%), payment cards (19%) discrete choice questions (26%) or bidding games (29%). Some form of construct validation tests, particularly associations between WTP and income, were done in 21 studies (50%). Conclusions: (i) The number of health care CVM studies is growing rapidly and the majority are done in the context of CBA; (ii) there is wide variation among health care CVM studies in terms of the types of questions being posed and the elicitation formats being used; (iii) classification and appraisal of the literature is difficult because reporting of methods and their relationship with the conceptual framework of CBA is poor; (iii) the applicability to health care of the CVM guidelines issued by the National Oceanic and Atmospheric Administration (NOAA) panel for environmental economics is unclear. © 1998 John Wiley & Sons, Ltd.

The paper discusses some methodological and measurement aspects with the contingent valuation (CV) method which appear to create problems when eliciting preferences for the relative social valuation of alternative health care programmes. After pointing to biases which tend to exaggerate the true valuations, emphasis is placed on framing issues when applied to health care. Thereafter the paper discusses the extent to which preferences elicited through one's willingness to pay can be used to infer how the respondent would prioritize between the health care programmes in question. New empirical evidence is presented which suggest discrepancies between a CV ranking and the ranking expressed when making a direct ordinal comparison.