Effect of substitutes in contingent valuation for a private market good

Economic theory predicts a decrease in valuation as the availability of substitutes increases. This paper describes a contingent valuation (CV) survey that investigates the effect of substitutes on valuation of private market goods. Using an approach that compares willingness to pay (WTP) values elicited from a CV question that accounts for substitutes with WTP values elicited from a similar question without substitutes, we find that allowing for substitutes can moderate WTP values. For the item valued in this study, a hamburger sandwich, allowing for substitutes was associated with a reduction of from 10% to 16% in stated values.     

Joint estimation of contingent valuation survey responses

Hanemann's utility difference model for the dichotomous choice contingent valuation method is modified to account for interrelationships between responses to a set of contingent valuation questions. A nonlinear seemingly unrelated regression model is presented to jointly estimate the probit models and to derive WTP from the CV responses. The model is used to test and impose restrictions derived from economic theory on the utility difference model. Mean WTP estimates for three different types of changes in the quality of California deer hunting were uniformly lower for the joint response probit model compared to a set of independent probit models.     

Trust, Responsibility and the Interpretation of Contingent Valuation Results

Responses to contingent valuation questionnaires are contingent on respondent perceptions of trust and responsibility regarding aspects of the scenario presented to them. These issues can influence CV responses in several ways, with the net effect on WTP estimates depending on the relative prevalence of the different opposing effects in a given application. Whether such effects are to be considered biases, to be removed where possible, depends on the notion of validity one adopts. Whilst issues of trust and responsibility may pose little threat to predictive notions of validity, they are more problematic from a surplus validity, cost-benefit, perspective. Further discussion of the pros and cons of different validity notions for contingent valuation is required.     

Sequencing and the Adding-up Property in Contingent Valuation of Endangered Species: Are Contingent Non-Use Values Economic Values?

This paper presents tests of the theoretical validity of the contingent valuation (CV) method. The validity of CV is especially a concern when involving environmental goods with a predominant non-use value. One test of theoretical validity is the adding-up property that implies that a specific good should be equally valued irrespectively of it is being valued directly or built-up sequentially. In this CV study four independent sub-samples stated willingness to pay for the same composite good, or package, using different sequences. One sub-sample valued the composite good directly, while two sub-samples faced built-up sequences valuing first subsets of this composite good. A fourth sub-sample valued the composite good from a dividing-out approach, facing first the valuation of a larger multi-package. Theoretically expected sequencing effects were observed; the subset goods obtained higher values earlier in a sequence, and the dividing-out approach decreased the stated value for the composite good. Most importantly, these CV data did pass the tests of the adding-up property.     

Valuing cultural heritage in developing countries: comparing and pooling contingent valuation and choice modelling estimates

A substantial part of the United Nation’s World Heritage Sites (WHSs) can be found in developing countries, but many of them are in a bad state. Thus, there is a need to document the social benefits of these global goods in order to justify the costs of restoration and preservation programmes (RPPs). This study adds to the scarce literature on economic benefits of WHSs in developing countries, and reduces the need to perform very uncertain benefit transfers from European or US valuation studies. We apply Contingent Valuation (CV) and Choice Modelling (CM) to estimate the social benefits of RPPs for the My Son world cultural heritage site in Vietnam; both to foreign visitors and the local residents. We then compare the estimates from the CV and CM methods, and pool the results from the two methods. The results show that both CV and CM are suited to estimating the economic benefits of preserving cultural heritage of My Son. The two methods produce very similar results, which can be interpreted as a test of convergence validity. The pooling results give evidence to show that the CV and CM models have the same underlying preference structures. Thus, these valuation models can be successfully used in cost-benefit analyses to assess the benefits to cultural heritage of measures to reduce air pollution, soil erosion, climate change and other causes to deterioration of cultural heritage sites.

Consumption Externalities in a Commercial Fishery: the Queensland Beam Trawl Fishery

Demand and contingent valuation models are used to analyze survey data obtained from a sample of recreational boat and shore fishers in southern Queensland. The value of the recreational fishery to the average fisher in the sample and the value of marginal increases in catches of target species are estimated. These estimates are used to calculate the value of Pigovian taxes representing the marginal cost of catch and congestion externalities imposed by the beam trawl fishery on the recreational fishery. The results suggest that the cost of these externalities does not justify the closure of the beam trawl fishery.     

Use of Contingent Valuation to Elicit Willingness-to-Pay for the Benefits of Developmental Health Risk Reductions

We report the results of several contingent valuation (CV) surveys to elicit willingness-to-pay values from the general public for risk reductions associated with decreases in exposure to a chemical, PCBs, in the environment. We also develop Quality Adjusted Life Years (QALYs) from the survey using both standard gamble and time-tradeoff elicitation methods to explore the relationship between QALYs and willingness-to-pay (WTP), and to develop QALY weights for subtle developmental effects. The results of the CV surveys are designed for incorporation into a case study of an integrated risk model to monetize the benefits of predicted risk reductions. Respondents showed a nearly proportional, positive relationship between decreasing the risk of a 6-point reduction in IQ (a standard measure of “intelligence”) and WTP, but showed a negative relationship between risk reduction and WTP for reading comprehension as an outcome. The range of mortality risks that respondents would accept on behalf of their (hypothetical) 10-year-old child is 2 in 10,000 to 9 in 1,000 per IQ point, and WTP per IQ point is $466 ($380, $520). QALY weights elicited via time tradeoff (reduction in life expectancy) were significantly different from QALY weights elicited via a standard gamble (p = 0.001). Respondents who answered questions about ecological endpoints first were willing to pay a small additional amount when asked about human health effects, but those respondents who answered questions about human health endpoints first were not willing to pay any additional amount when subsequently asked about ecological effects. This paper has not been submitted elsewhere in identical or similar form, nor will it be during the first three months after its submission to the Publisher.     

Empirical Evidence Showing The Relationships Between Three Approaches for Pollution Control

Willingness to pay models have shown the theoretical relationships between the contingent valuation, cost of illness and the avertive behaviour approaches. In this paper, field survey data are used to compare the relationships between these three approaches and to demonstrate that contingent valuation bids exceed the sum of cost of illness and the avertive behaviour approach estimates. The estimates provide a validity check for CV bids and further support the claim that contingent valuation studies are theoretically consistent.     

Preference uncertainty in contingent valuation

In this paper, the results of empirical studies that applied two widely used methods - numerical certainty scale (NCS) and polychotmous choice (PC) - for estimating preference uncertainty adjusted willingness to pay (WTP) in contingent valuation (CV), are summarized. For this review, a number of conclusions are reached. First, there is a lack of consensus about which method is more appropriate for measuring preference uncertainty. Second, although preference uncertainty information has been found useful in detecting the incidence of hypothetical bias in CV studies, a consensus about a standard certainty threshold (or treatment mechanism) at which hypothetical behaviour converges to real behaviour is yet to emerge. Third, insufficient empirical evidence exists about the causal relationship between preference uncertainty scores and the theoretically expected explanatory variables. Finally, the preference uncertainty adjusted PC and NCS models fail to provide a consistent and more efficient welfare estimate compared to the conventional dichotomous choice certainty model.     

Do protest responses to a contingent valuation question and a choice experiment differ?

It is suggested that the number of protest responses in stated preference surveys depends, inter alia, on the valuation method used. Choice Experiments (CE) are said to generate a lower number of protest responses than Contingent Valuation (CV). However, no comparison of both methods with respect to protest responses has been conducted to date. We used both CE and CV in a survey on forest biodiversity in two German regions. Protest beliefs were measured for all respondents irrespective of whether they were willing to pay or not. The results show no clear pattern of differences between CE and CV regarding protest beliefs and protest responses. Using an attitude scale based on respondents’ protest beliefs, we see a significant negative effect of this attitude on willingness to pay in both methods. However, in one of the two study regions, the effect is weaker in CE than in CV.      

Proportionality of Willingness to Pay to Small Changes in Risk: The Impact of Attitudinal Factors in Scope Tests

Sensitivity (proportionality) of willingness to pay (WTP) to (small) risk changes is often used as a criterion to test for valid measures of economic preferences. In a contingent valuation (CV) study conducted in Austria, 1,005 respondents were asked their WTP for preventing an increase in the risk of being killed in an avalanche of 1/42,500 and 3/42,500 respectively. WTP for the higher variation in risk is significantly greater than WTP for the lower risk change. We find evidence that those respondents who have had personal experience of avalanches in recent years combine the information about future risk increase—as provided in the survey—with the observed number of fatal avalanche accidents in the past. Proportionality of WTP holds if such prior experience is taken into account and if attitudinal factors in scope tests are controlled for. This research was funded by alpS GmbH—Center for Natural Hazard Management, Innsbruck, Austria.     

The validity of the contingent valuation method: Perfect and regular embedding

This article deals with one aspect of the validity claim of the contingent valuation method, namely: to what extent does the method produce different values in situations for which economic theory claims different values. Two aspects of this validity test — perfect and regular embedding — were tested in a field experiment comprising six samples of the Dutch population. Perfect embedding occurs when the value for a specific good is similar to the value for a more inclusive good. Perfect embedding did not manifest itself in the experiment. Respondents considered a package of six goods as well as a package of two goods more valuable than one of these goods. It is argued that this supportive evidence of the method's validity claim occurred because the goods involved were well-defined. Regular embedding occurs when the same good receives a lower value if the value for it is inferred from the value for a more inclusive good rather than if that good is valued on its own. Regular embedding was only found when respondents were given the opportunity to value the inclusive good before valuing the specific good. Respondents who were given information on the inclusive good without valuing it did not state different values than respondents who were not given that information. It seems that respondents perceive an inclusive good as being relevant to their valuation decision only when they are asked to value it. Further research is necessary to shed more light on the underlying processes that may account for this.     

Asking for Individual or Household Willingness to Pay for Environmental Goods?

The aggregate welfare measure for a change in the provision of a public good derived from a contingent valuation (CV) survey will be higher if the same elicited mean willingness to pay (WTP) is added up over individuals rather than households. A trivial fact, however, once respondents are part of multi-person households, it becomes almost impossible to elicit an “uncontaminated” WTP measure that with some degree of confidence can be aggregated over one or the other response unit. The literature is mostly silent about which response unit to use in WTP questions, and in some CV studies it is even unclear which type has actually been applied. We test for differences between individual and household WTP in a novel, web-administered, split-sample CV survey asking WTP for preserving biodiversity in old-growth forests in Norway. Two samples are asked both types of questions, but in reverse order, followed by a question with an item battery trying to reveal why WTP may differ. We find in a test between samples that the WTP respondents state on behalf of their households is not significantly different from their individual WTP. However, within the same sample, household WTP is significantly higher than individual WTP; in particular if respondents are asked to state individual before household WTP. Our results suggest that using individual WTP as the response unit may overestimate aggregate WTP. Thus, the choice of response format needs to be explicitly and carefully addressed in CV questionnaire design and further research in order to avoid the risk of unprofitable projects passing the benefit-cost test.

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Treating respondent uncertainty in contingent valuation: A comparison of empirical treatments

This research examines the impact of uncertainty on contingent valuation responses using (1) a survey of Canadian landowners about willingness to accept compensation for converting cropland to forestry and (2) a survey of Swedish residents about willingness to pay for forest conservation. Five approaches from the literature for incorporating respondent uncertainty are used and compared to the traditional random utility model with assumed certainty. The results indicate that incorporating uncertainty has the potential to increase fit, but could introduce additional variance. While some methods for uncertainty can be an improvement over traditional approaches, it is imperative to exercise caution when making systematic judgments about the effect of uncertainty on contingent valuation responses.     

Do Colored Photographs Affect Willingness to Pay Responses for Endangered Species Conservation?

The NOAA panel suggested that use of photographs should be pre-tested to explore their effects on subjects (Arrow et al. 1993). For this paper, a modification to the test suggested by the NOAA Panel was made. We tested whether use of colored, as opposed to black and white (B & W), photographs influence respondents’ valuation of the environmental commodity in question. The context of the test is a CVM study valuing the benefits from protecting the national bird. This was performed using two drop-off surveys that were identical except for the color of the photographs incorporated in the survey instrument. The dichotomous choice logit equations were statistically different between the two treatments of the questionnaire, indicating the significant effect of colored photographs on the respondents’ WTP. The findings support the NOAA Panel recommendation of careful pre-testing and scrutiny of the photographs integrated in the questionnaire since ‘packaging’ of the environmental good (i.e., endangered species protection) matters in valuing benefits associated with it. Since colored photographs are found to be value-enhancing, to simply use B & W photos as an attempt to reduce cost associated with implementing the contingent valuation (CV) survey, especially when limited research money is involved, would result to lower the estimated value of the environmental good.     

Protesting and Justifying: A Latent Class Model for Contingent Valuation with Attitudinal Data

This article develops a latent class model for estimating willingness-to-pay (WTP) for public goods using simultaneously contingent valuation (CV) and attitudinal data to identify individuals with similar characteristics, such as WTP and protest attitudes. We find evidence that the answer to the CV question influences the responses to the attitudinal questions. In our case, this influence reflects rational behavior (budget constraint issues) and justification biases related to protest reasons, such as lack of trust in institutions or fairness issues with respect to the distribution of the burden of preservation. The results from our empirical application confirm the importance of accounting for those biases.     

Modelling Heterogeneity and Uncertainty in Contingent Valuation: an Application to the Valuation of Informal Care

Both the lack of market data and the need to adopt a more holistic approach in the valuation of non‐market activities within health care have pointed towards the use of contingent valuation (CV) methods. However, to date, few studies have employed such techniques to value informal care, despite its provision being an important public policy question. We propose an analytical framework that through the use of random parameters models and respondents' certainty scales can incorporate both unobserved and observed heterogeneity in the CV modelling. This is the first CV study of informal care for Scotland (UK) and a £7.68 per hour value is estimated.     

Reducing protest responses by deliberative monetary valuation: Improving the validity of biodiversity valuation

This paper focuses on examining the validity of biodiversity valuation methodologies. The results of a group deliberation technique (deliberative monetary valuation) are compared to those derived from a contingent valuation (CV) survey using the same environmental topic. Evidence is here presented that DMV can address some of the limitations of CV; namely a prevalence for lexicographic preference ordering due to psychological reasons and the lack of a priori or well-formed preferences. Both of these methodological shortcomings can result in protest responses which decrease the external validity of results. It is common environmental valuation methodology practice to exclude protest responses from the analysis on the grounds that they are illegitimate choices, thus the sample and consequently the environmental valuation analysis may become less representative of the population. An advantage of the DMV methodology is that it was found to significantly reduce the rate of protest responses to less than half (from 29% to 13%). Furthermore, DMV significantly increased the proportion of positive bids but not the amounts contributed. In relation to preference formation issues, we suggest rethinking the current practice of the DMV method, and propose dedicating the entire initial discussion session to introducing the good outside of a valuation context.     

Complements, Substitutes, Budget Constraints and Valuation

This study employs a multi-program contingent valuation (CVM) design tosimultaneously assess the value of three ecosystem conservation programsin Alberta, Canada. The design is different from most other CVM designsand has several different features including the natural incorporation ofdirect reminders of substitute/complementary programs and budgetconstraints. In contrast to the findings of other studies, two of the environmentalprograms appear to be complements and other combinations of the programssuggest an absence of substitution effects. The multi-program model ismore informative and robust in terms of theoretical validity and expectedrelationships with demographic and recreational characteristics of therespondents.     

Comparing continuous and discrete contingent valuation questions

This paper explores two commonly used methods to elicit an individual's willingness to pay (WTP) for a public good in contingent valuation studies. Currently, the most preferred method is the take-it-or-leave valuation question, or discrete valuation question (DVQ), where the respondent accepts or rejects a suggested cost for the good. The traditional method, the continuous valuation question (CVQ), simply asks an individual to state his WTP for the suggested change in the provision of a public good like cleaner air. We introduce a simple way to compare the results from these two methods. We also test the anchoring behavior suggested in the psychological literature on choice under uncertainty. The results do not support the anchoring hypothesis, but suggest the hypothesis that people perceive the two tested valuation questions differently.I would like to thank Prof. Glenn Harrison, University of South Carolina, Prof. P-O Johansson, Stockholm School of Economics, Prof. Jason Shogren, Iowa State University, and two referees for helpful comments. The usual disclaimer applies.