Consistency and construction in stated WTP for health risk reductions: A novel scope-sensitivity test

A contingent valuation study is conducted to estimate willingness to pay (WTP) for reducing skin cancer risks. A split sample design contrasts dichotomous choice (DC) with open-ended (OE) methods for eliciting WTP. A novel scope test varies the remit of risk reductions from just the individual respondent to their entire household allowing us to examine both the statistical significance and scale of scope sensitivity. While OE responses fail such tests, DC responses pass both forms of testing. We conclude that conformity of the size of scope effects with prior expectations should form a focus for future validity testing.     

Modeling self-censoring of polluter pays protest votes in stated preference research to support resource damage estimations in environmental liability

The identification and treatment of protest response in stated preference (SP) research such as contingent valuation is an underdeveloped area. Protest related to the polluter pays principle (PPP) is expected to pose an important hurdle to the application of SP research in environmental liability claims, for instance under the European Environmental Liability Directive. Our main objective is to test the effect of PPP induced protest votes on welfare measures for lost passive use value using different treatment procedures. We argue for a more reliable and defensible indicator of willingness to pay (WTP) in environmental liability litigation cases than current standard removal practices in cases where protest votes affect sample representativeness. Analyzing the impact of PPP-based protest response on WTP values with the help of a Full Information Maximum Likelihood sample selection model, a significant correlation is found between the decision to participate in the CV market and the WTP bids. Self-censoring biases average WTP and is correlated with factors such as respondent use of the resource and disposition towards its future protection. Simply removing protest response from the sample is indefensible and results in a biased estimation of WTP.     

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.     

Willingness to Pay and Sensitivity to Time Framing: A Theoretical Analysis and an Application on Car Safety

Stated preference (SP) surveys attempt to obtain monetary values for non-market goods that reflect individuals’ “true” preferences. Numerous empirical studies suggest that monetary values from SP studies are sensitive to survey design and so may not reflect respondents’ true preferences. This study examines the effect of time framing on respondents’ willingness to pay (WTP) for car safety. We explore how WTP per unit risk reduction depends on the time period over which respondents pay and face reduced risk in a theoretical model and by using data from a Swedish contingent valuation survey. Our theoretical model predicts the effect to be nontrivial in many scenarios used in empirical applications. In our empirical analysis we examine the sensitivity of WTP to an annual and a monthly scenario. Our theoretical model predicts the effect from the time framing to be negligible, but the empirical estimates from the annual scenario are about 70 % higher than estimates from the monthly scenario.     

Trading Taxes vs. Paying Taxes to Value and Finance Public Environmental Goods

The potential sensitivity of environmentalresource valuation to payment vehicles is ofinterest to researchers and decision-makersinvolved in estimating and applying thesenumbers. A conceptual model is developed whichprovides insight into how the different paymentvehicles of a special tax and a taxreallocation affects the willingness to pay(WTP) for environmental goods. Hypothesistesting using contingent valuation datasuggests WTP with a tax reallocation is higherthan WTP with a special tax for ground waterquality protection in Georgia and Maine, USA.Technical measurement and welfare analysisimplications and limitations of valuing andfinancing public environmental goods using taxrealloactions are discussed.     

The impact of the bird flu on public willingness to pay for the protection of migratory birds

In this paper, we present the results of a unique time series analysis of contingent values and models for migratory bird protection based on an identical contingent valuation (CV) survey carried out over a three year time period since the first bird flu outbreak in 2003. Although there exists no scientific evidence for a direct relationship, migratory birds are believed to play an important role in spreading the bird flu virus worldwide. The time series analysis allows us to test the temporal stability of stated preferences for migratory bird protection and at the same time examine indirectly the possible impact of increased media attention and public awareness levels regarding the bird flu. We test the impact of the bird flu on public willingness to pay (WTP) for migratory bird protection in the final 2005 survey whilst accounting for procedural variance introduced by sequencing and question ordering-effects, but we are unable to demonstrate a direct negative relationship. A novelty of the study presented here is that respondents in the CV surveys are given the opportunity to pay an annual money amount or a one-time-off lump-sum. Annual WTP values appear to be significantly higher than one-time-off WTP values, suggesting a negative implicit discount rate. Self-selection bias is an important reason for the observed differences. We find that respondents who agree to pay annually differ significantly from respondents who wish to pay a lump-sum in terms of their underlying preferences and motivations towards migratory bird protection.     

Ordering effects in contingent valuation surveys

This paper focuses on ordering effects in CVM surveys; how the expressed value of a particular good valued in a sequence of several goods depends on where in the sequence the good is valued. We use data from a Norwegian CVM survey focusing on WTP for a 50% reduction in air pollution from car traffic to test for the existence of ordering effects and to apply a test for internal consistency. We found considerable and significant ordering effects in our data, but were not able to reject the hypothesis of internal consistency. Based on our survey, we argue that ordering effects may be a result of rational choice. These effects are problematic if a sequential valuation procedure is applied to a simultaneous problem, and/or the respondents are given imperfect information about the decision problem.     

The missing piece: Valuing averting behavior for children's ozone exposures

Individuals can reduce their exposure to air pollution by reducing the amount of time they spend outdoors. Reducing outdoor time is an example of an averting behavior that should be measured as part of willingness to pay (WTP) for improvements in air quality. In this paper, we estimate parents’ WTP to prevent restrictions on a child's outdoor time from a stated-preference (SP) conjoint survey. We combine this WTP measure with an estimate of reductions in time spent outdoors on high-ozone days from an activity-diary study to estimate this averting behavior component of WTP for reductions in ozone pollution.     

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.     

The total economic value of threatened, endangered and rare species: An updated meta-analysis

This paper updates a 1996 meta-analysis of studies using the Contingent Valuation Method (CVM) to value threatened, endangered and rare species published in this journal by Loomis and White. A variable for studies conducted in or after 1995 was added to the model to test if new studies are systematically different from old studies and identify which explanatory variables influencing willingness-to-pay (WTP) for these species have changed over time. Generally newer studies yielded higher WTP. Variables such as the change in the size of the species population, payment frequency, survey mode, response rate, type of respondent, type of species, and a new variable for whether a species is a ‘charismatic megafauna’ or not, whether the species has use and nonuse value versus nonuse value only and year of the study, were found to significantly influence WTP. This model is used in a benefit transfer example and a comparison of original study estimates and model estimates is made to compare its accuracy. The average within sample benefit transfer error was 34-45%.     

HOW KNOWLEDGE AFFECTS PAYMENT TO CONSERVE AN ENDANGERED BIRD

The paper reports the findings of an experimental survey conducted to determine the public's willingness to pay (WTP) for the protection and conservation of the golden-shouldered parrot in Australia. This parrot is endemic to Australia and is one of Australia's most endangered birds. The paper examines the public's knowledge of this parrot and compares it with other endangered birds as well as common birds and the public's WTP for conservation from a hypothetical allocation of money based on their current knowledge. We then examine how this allocation changes with increased knowledge about all species.     

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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Fairness in the contingent valuation of environmental public goods: attitude toward paying for environmental improvements at two levels of scope

Respondents to contingent valuation (CV) surveys give a variety of reasons for not wanting to pay money. This variability is likely to reflect people's attitudes toward paying for the public good change, their attitudes toward paying for public goods in general, and a component that is independent of these attitudes but unique to particular beliefs about paying (e.g. ‘I can't afford to pay’). Negative attitudes toward paying can contribute to an apparent insensitivity to different levels of the same public good. In a telephone survey, northern Wisconsin property owners were asked about their WTP for four environmental public goods (biodiversity, Indian spearfishing, water quality, and wolves) at two levels of scope (part and whole). For water quality and spearfishing, the part was a chain of lakes that was geographically nested within a larger region of lakes. Similarly, the biodiversity whole represented a region comprising the smaller level of the public good. The scope conditions for wolves were quantitatively nested levels of returning 300 and 800 wolves to northern Wisconsin. Respondents’ beliefs about paying for each public good and level of scope were measured in order to test their generality across the different public goods and levels of scope. Negative attitudes toward paying that are general across public goods place restrictions on the use of CV for environmental public goods. However, negative attitudes that are tied to specific environmental public goods suggest that the valuation method might be difficult to implement in these cases only. Moreover, negative attitudes toward paying that are either general or specific may contribute to perfect embedding when they are expressed across different levels of scope for the same public good. Respondents' beliefs about paying for each public good were associated with an attitude toward paying for the respective good and an attitude toward paying for public goods in general at both levels of scope. The general attitude was more explanatory of beliefs about paying for wolf reintroduction and spearfishing than were the specific attitudes. The distribution of beliefs was sensitive to the type of good being valued, but less so to the scope of the public good change. Contingent valuation practitioners should seek improvements in respondents' perceptions of the fairness of the valuation process in order to facilitate citizens' involvement in decisions about environmental public goods. Avenues for future research are proposed and discussed.     

A convergent validity test within the payment card format using simulation techniques

A convergent validity test is performed between two groups of versions of the payment card format. The first group, the classic payment card (CPC), asks respondents to report their willingness to pay (WTP) as a point from a list of amounts, and then treats each WTP response as an interval. The second group generates WTP data that may contain both single point and interval values. It includes the two-way-payment ladder (TWPL) (respondents have to tick amounts they would definitely pay and cross amounts they would definitely not pay), and point-interval payment card (PIPC) (respondents have to tick their WTP as either a point or an interval). The test is conducted using data from one TWPL study and two PIPC studies. For each study, we use WTP values stated to simulate 200 CPC WTP datasets, which allows controlling for any behavioral biases likely to confound the outcome of the test. The results challenge the conventional way of eliciting WTP under the CPC and the typical way of treating WTP data from this PC version. Although convergent validity holds between the TWPL/PIPC and CPC, parameter and mean WTP estimates from the TWPL and PIPC are more stable as PC intervals widths increase.     

Marine Debris, Beach Quality, and Non-Market Values

This paper reports the first attempt to measure the importance of controlling marine debris as an aesthetic characteristic of beaches and coastal area. The results are based on a contingent valuation survey designed to estimate the economic value people would place on controlling marine debris on recreational beaches in New Jersey and North Carolina. A Weibull survival model was estimated treating for and against votes as defining censoring points for an unknown willingness to pay distribution. The findings suggest: (1) people do distinguish situations with differing amounts of debris when they are described using color photographs; (2) the pilot survey implies measures of people's willingness to pay (WTP) for debris control are consistent with a scope test in that larger WTP is associated with programs intended to address situations for more serious background levels of debris; and (3) local beach conditions seem to influence how people interpreted the plans describing beach conditions without the proposed control programs.     

Multivariate Mixed Models for Open-Ended Contingent Valuation Data: Willingness To Pay For Conservation of Monk Seals

Although dichotomous choice (DC) contingent valuation (CV) has been recommended by the US NOAA 'blue-ribbon' panel for large-scale contingent valuation studies, useful information can still be obtained from smaller, open-ended (OE) studies, often undertaken as a precursor to a DC survey. The CV study considered here was carried out in Greece and looked at willingness-to-pay (WTP) for protecting the Mediterranean monk seal (Monachus-monachus) in the Aegean area. This is the most endangered seal in the world, and the application of the CV methodology was the first such application in Greece. The OE data consist of two responses: first, a binary response detailing whether or not respondents were in principle prepared to pay for the protection of this seal; secondly, those respondents who answered 'yes' to the first question were then asked to state their maximum WTP for such protection. A multivariate binomial – log-normal mixture model is used to develop a bid function including explanatory variables such as income, sex, age and education. Such a modelling approach provides an alternative to more commonplace tobit estimation. However, the model is extended to include further information which was collected on:(a) an increased WTP amount given in response to information that the initial WTP amount may not be enough to prevent the extinction of the seal;(b) respondents were asked to divide their final WTP amount between use, option and existence values, the latter requiring a multivariate model with four binary and four continuous responses per individual in the same model.The discussion focuses on the methodological issues raised with some comment on the substantive interpretation of results.     

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.     

Identifying the scope effect on a meta-analysis of biodiversity valuation studies

Insensitivity to scope is an issue of much debate in contingent valuation (CV) even today. Although the literature about insensitivity to scope is abundant, the reasons for it are not yet well known. Through a meta-analysis of CV studies of biodiversity, the treatment of the different possible measures of the quantity of the good is explored in relation to scope sensitivity. Overall, the findings suggest that CV results are sensitive to the amount of the good being valued, although the result depends on how the environmental change is measured. Results support the use of absolute sizes when conducting CV studies.     

Is the Income Elasticity of the Willingness to Pay for Pollution Control Constant?

How willingness to pay for environmental quality changes as incomes rise is a central question in several areas of environmental economics. This paper explores both theoretically and empirically whether or not the willingness to pay (WTP) for pollution control varies with income. Our model indicates that the income elasticity of the marginal WTP for pollution reduction is only constant under very restrictive conditions. Our empirical analysis tests the null hypothesis that the elasticity of the WTP for pollution control with respect to income is constant, employing a multi-country contingent valuation study of eutrophication reduction in the Baltic Sea. Our findings reject this hypothesis, and estimate an income elasticity of the WTP for eutrophication control of 0.1–0.2 for low-income respondents and 0.6–0.7 for high-income respondents. Thus, our empirical results suggest that the elasticity is not constant but is always less than one. This has implications for how benefits transfer exercises, and for theoretical explanations of the environmental Kuznets curve.     

Are There Income Effects on Global Willingness to Pay for Biodiversity Conservation?

This paper is concerned with the empirical relationship between biodiversity conservation values and income. We use random effects panel models to examine the effects of income, and then GDP per capita, on willingness to pay for habitat and biodiversity conservation. In a meta-analysis, 145 Willingness To Pay estimates for biodiversity conservation where existence value plays a major role were collected from 46 contingent valuation studies across six continents. Other effects included in the meta-analysis were the study year; habitat type; continent; scope as presented to respondents; whether WTP bids were for preventing a deterioration or gaining an improvement in conservation, whether a specific species or specific habitat was protected; whether the questionnaire used a dichotomous choice or an open-ended format; distribution format; and the choice of payment vehicle. GDP per capita seemed to perform as well as an explanatory variable as respondent’s mean stated income, indicating that it is wealth in society as a whole which determines variations in WTP. Even if large variation, our main conclusion is, that the demand for biodiversity conservation rises with a nation’s wealth, but the income elasticity of willingness to pay is less than one.