A Comparison of Value Elicitation Question Formats in Multiple-Good Contingent Valuation

This paper provides a convergent validity test of two types of multinomial choice questions vis-a-vis a dichotomous choice question by formally testing whether these stated preference elicitation question formats provide comparable welfare estimates. In particular, a dichotomous choice question, a traditional multinomial choice question, and a modified multinomial choice question suggested by Carson and Groves （2007） were applied in split samples to assess the influence of the informational and incentive properties on the respondents＇ annual willingness to accept compensation for adopting costly conservation practices in agriculture that benefit the environment. Our findings suggest that the two multinomial choice question formats elicit a similar mean willingness to accept distributions, but they are both different from a standarddichotomous choice question. Further, the willingness to accept distributions derived from the multinomial choice question formats are more dispersed than those from the dichotomous choice question.     

Theoretical incentive properties of contingent valuation questions: Do they matter in the field?

Green et al. (1998) [Green, D., Jacowitz, K.E., Kahneman, D., McFadden, D., 1998. Referendum contigent valuation, anchoring, and willingness to pay for public goods. Resource and Energy Economics 20 (2), 85−116] show theoretically that stated preference questions about public services can be framed in such ways that if the subjects accept the frame the payoff­maximizing behavior will be to answer truthfully. One key element of such a theoretically incentive­compatible framing is that the (hypothetical) decision rule specified in the survey instrument is understood to be a majority rule rather than the efficiency rule typically used in cost­benefit analysis. We conducted field experiments in Germany and Switzerland to test if a referendum framing as suggested by Green et al. is effective in reducing strategic misrepresentation in a contingent valuation setting. We did not find the expected effects of the framing treatments on stated willingness to pay or on individuals' (stated) beliefs about the social choice context. The results do not support hopes that a theoretically incentive compatible framing could be purposefully used to invoke the specific beliefs about the linkage between responses and policy implementation that would make stated preference questions incentive compatible.     

Repeated Dichotomous Choice Formats for Elicitation of Willingness to Pay: Simultaneous Estimation and Anchoring Effect

Repeated dichotomous choice contingent valuation data are generated from responses to a succession of binary questions regarding alternative prices for an environmental good. In this paper we propose a simultaneous equation model that allows for endogeneity and error correlation across the responses at each stage of the bidding process. The model allows us to study the evolution of anchoring effects after the second dichotomous choice question. Estimation involves the Bayesian techniques of Gibbs sampling and data augmentation, and the application focuses on the preservation value of a natural area. The results for a data set involving up to four successive dichotomous choice questions show that restricted multiple-bounded models are rejected by the data with the general model. In addition, willingness to pay tends to stabilize after the second stage in the elicitation process for the general unrestricted model. When taking anchoring effects into consideration, it is revealed that individuals’ responses in the latter stages are influenced by the sequence of bid prices offered in earlier questions. Nevertheless, they do not have a significant effect on welfare estimates.      

Estimating the economic benefits of acidic rock drainage clean up using cost shares

This paper reports the results of a stated preference study that estimates the economic value for cleaning up acid rock drainage in Colorado's Snake River watershed. In contrast to much of the existing literature, the present study emphasizes benefit estimation for three implementing projects rather than benefit estimation for general changes in water quality or large scale water quality policy. The focus on implementing projects delivers information that is specifically relevant to current decisions being faced in the watershed. While valuation questions in most stated preference studies present costs that have no relation to actual project costs, this study presents a new cost share approach. Project costs are estimated and then valuation questions present different local cost shares to subjects. This approach facilitates stated cost variation necessary for estimating the mean of the distribution of project values without resorting to experimentally designed, fictitious stated costs. In addition to estimating the mean value, which facilitates benefit cost analysis, the study also provides median value estimates, which provide insights into the political feasibility of these projects. Study results suggest that local cost shares on the order of 20%-40%, depending on the project, are politically feasible.     

A multilevel modelling approach to triple-bounded dichotomous choice contingent valuation

The use of dichotomous choice (DC) questions in the elicitation of willingness to pay (WTP) in contingent valuation studies is common practice at the present time. Recent research has shown that double-bounded DC questions provide statistically superior results to single-bounded questions, given an appropriate sampling design. This paper uses a relatively new multilevel modelling technique to analyze a triple-bounded DC design, which in addition includes an initial non-monetary question on whether an individual accepts, in principle, a WTP some unspecified amount. The theoretical basis of the multilevel model used is described, and some of the possibilities of this potentially powerful and versatile technique are discussed. The practical operation of the multilevel model is demonstrated using data from a contingent valuation study conducted in the Norfolk Broads, England, an internationally important wetland resource.     

Starting point bias and respondent uncertainty in dichotomous choice contingent valuation surveys

In this article, we develop a dichotomous choice model with follow-up questions that describes the willingness to pay being uncertain in an interval. The initial response is subject to starting point bias. Our model provides an alternative interpretation of the starting point bias in the dichotomous choice valuation surveys. Using the Exxon Valdez survey, we show that, when uncertain, individuals tend to answer “yes”.     

A Semi-parametric Estimator of Willingness-to-pay Applied to Dichotomous Choice Contingent Valuation Data

The use of dichotomous choice questions (Are you willing to pay $x?) has been advocated as superior to open ended questions (What would you be willing to pay?) in contingent valuation studies of non‐market goods. A supplementary dichotomous choice question, raising or lowering the bid price depending on the initial response, gives increased precision. However, a problem with these methods is that identifying the mean willingness to pay (WTP) is more complex, and often conditional on making a distributional assumption. This paper will present a semi‐parametric method for estimating WTP without invoking any such assumptions, using the interval inherent in the double bounded format, and based on estimating the underlying hazard function for the distribution of WTP. An advantage of the approach over other non‐parametric methods is that it allows one to include respondent characteristics as determinants of the individual decisions, and does so within a computationally straightforward framework.     

Nonparticipation or Misspecification? The Impacts of Nonparticipation on Dichotomous Choice Contingent Valuation

Dichotomous choice (or Referendum) contingent valuation surveys have become the predominate choice for valuing goods and services otherwise not valued in a standard market (nonmarket goods and services). A number of researchers have recently recommended that dichotomous choice contingent valuation studies include a follow-up question to all no responses to determine whether the no response is a result of unwillingness to pay, or nonparticipation. If the goal of the study is to investigate the impact of covariates on either mean willingness to pay or the probability of nonparticipation, simple identification of indifferent individuals will not suffice. A simulation study shows that existing econometric models designed to account for nonparticipation are extremely sensitive to misspecification bias. Accurate identification of the probability of nonparticipation is hampered by potential misspecification of the distribution of willingness to pay.     

Construct Validity of Dichotomous and Polychotomous Choice Contingent Valuation Questions

In this note we conduct construct validity tests for dichotomous choice (DC) and polychotomous choice (PC) contingent valuation questions. Contrary to previous results, we find that DC and PC estimates of willingness to pay are theoretically valid, convergent valid, and similar in terms of statistical precision. Similar to previous results, PC respondents are less sensitive to information than DC respondents. We conclude that DC and PC valuation questions are construct valid for this study. Sequential PC valuation questions could be used in studies where obtaining information about the certainty or intensity of respondent preferences would be useful.     

Willingness to Pay and the Cost of Commitment: An Empirical Specification and Test

In a static setting, willingness to pay for an environmental improvement is equal to compensating variation. In a dynamic setting, however, willingness to pay may also contain a commitment cost. In this paper we incorporate the dynamic nature of the value formation process into a stated preference study designed to test whether there is an important dynamic component (commitment cost) in stated preference values. The results clearly indicate that stated preference values can contain commitment costs and that these can be quite large: respondents offered the opportunity to delay their purchasing decisions until more information became available were willing to pay significantly less for improved water quality than those facing a now-or-never decision. These results have important consequences for the design and interpretation of stated preference data.     

A Bayesian Approach to Double Bounded Contingent Valuation

In this paper we propose a Bayesian approach to model double bounded contingent valuation data. The double bounded elicitation method is interpreted as a two tier iterated process in which the subject is allowed to have a second thought about his/her valuation for the environmental good. Prior information is modelled from the answers to the first dichotomous choice question. The model is Quasi-Bayesian (Q-B) in that the prior distribution refers to mean willingness to pay while the likelihood function refers to the proportions of a multinomial distribution. This model is applied to empirical data from a contingent valuation survey involving the valuation expressed by European tourists for access to natural areas in the Canary Islands. Results show that point estimate of consumer surplus computed with the Q-B model does not differ substantially from single bounded model estimation. In addition, double bounded seems to be quite robust to the choice of the prior model of willingness to pay responses. Comparison with open ended suggests that the Q-B model might be useful to control for strategic response and starting point biases.     

Does don't know mean no? Analysis of 'don't know' responses in dichotomous choice contingent valuation questions

The ‘don't know’ response option in contingent valuation dichotomous choice questions is analysed using data from both willingness to pay and willingness to accept studies. An empirical analysis is conducted to determine whether respondents are stating a response similar to yes or no responses or a middle response. It is found that don't know responses are similar to no responses in the willingness to pay study. In the willingness to accept study, it is found that the ‘don't know’ responses are similar to a middle response. It is further suggested that researchers consider calculating ambivalence bounds when a don't know response is a middle response.     

A Contingent Valuation Estimate of the Benefits of Wolves in Minnesota

In this paper we estimate the willingness topay for a wolf management plan and a wolfdamage plan in Minnesota using the contingentvaluation method. The theoretical definition ofwillingness to pay for wolf protection iscomposed of use and non-use values. Weincorporate a don't know response option in thedichotomous choice valuation questions. A largenumber of respondents answered don't know. Themultinomial logit model is used todifferentiate between don't know and noresponses. Non-use motives are importantfactors that explain willingness to pay. We usethese benefit estimates in combination with twoalternative cost estimates to consider theefficiency of the wolf management and damageplans. Both plans have estimated benefitsgreater than costs.     

A comparison of contingent valuation method and random utility model estimates of the value of avoiding reductions in king mackerel bag limits

This paper estimates the value of king mackerel bag limit changes with both stated and revealed preference methods. The 1997 Marine Recreational Fishery Statistical Survey allows estimation of the value of avoiding bag limit reductions with the random utility model and the contingent valuation method. Using the contingent valuation method, the willingness to pay to avoid a one fish reduction in the bag limit is $2.45 per year. Using the random utility model, the willingness to pay to avoid a one fish reduction in the bag limit is $2.24 per trip and $7.71 for a two-month time period. Considering several methodological issues, the difference in willingness to pay between the stated and revealed preference methods is in the expected direction.     

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.     

A comparison of responses to single and repeated discrete choice questions

According to neoclassical economic theory, a stated preference elicitation format comprising a single binary choice between the status quo and one alternative is incentive compatible under certain conditions. Formats typically used in choice experiments comprising a sequence of discrete choice questions do not hold this property. In this paper, the effect on stated preferences of expanding the number of binary choice tasks per respondent from one to four is tested using a split sample treatment in an attribute-based survey relating to the undergrounding of overhead low-voltage electricity and telecommunications wires. We find evidence to suggest that presenting multiple choice tasks per respondent decreases estimates of expected willingness to pay. Preferences stated in the first of a sequence of choice tasks are not significantly different from those stated in the incentive compatible single binary choice task, but, in subsequent choice tasks, responses are influenced by cost levels observed in past questions. Three behavioural explanations can be advanced – weak strategic misrepresentation, reference point revision, and asymmetric value learning. The evidence is contrary to the standard assumption of truthful response with stable preferences.     

Stated Preferences, Real Behaviour and Anchoring: Some Empirical Evidence

We compare different contingent valuation question formats with each other and with observed behaviour for a non-monetary estimation task, the expected number of kilometers travelled by automobile. Open-ended questions, open-ended follow-up questions, dichotomous choice (DC) questions, and double-bound DC questions are included. The single and double-bound DC questions result in an estimated mean about twice as high as the actual value and the open-ended mean. The DC question overestimation seems to be due to an anchoring effect leading to yea-saying behaviour. Our results about the difference between DC questions and open-ended questions is consistent with the pattern observed in contingent valuations studies of the willingness to pay. Our results indicates that DC questions seem to be associated with a general overestimation problem that is present even for simple non-monetary estimation tasks.     

What to Value and How? Ecological Indicator Choices in Stated Preference Valuation

The ecological literature accepts that many policy outcomes cannot be observed directly and must be characterized using indicators. Multiple indicators can often be used to communicate similar ecological outcomes. Previous studies using alternative indicators in stated preference surveys suggest that welfare estimates may be indicator-dependent, casting doubt on whether welfare estimates are sufficiently reliable for cost benefit analysis. We suggest that the reason for such indicator dependence may be that indicators used in these prior studies represented different outcomes valued by respondents. This possibility underscores the need for greater attention to selection of indicators and their properties within stated preference survey design. This paper develops a model introducing the concept of outcome equivalent indicators, defined as indicators that provide alternative representations of identical underlying outcomes. To assess empirically whether welfare estimates are indeed robust to indicator choice when alternative indicators are expected to be outcome equivalent, we analyze data from a choice experiment estimating willingness to pay for migratory fish restoration in Rhode Island, USA. Results demonstrate that welfare estimates are robust to the use of alternative ecological indicators within stated preference scenarios.     

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.      

Induced-Value Tests of Contingent Valuation Elicitation Mechanisms

Using an induced-value experimental design that varies whether values for a “good” are certain or uncertain and whether payment is real or hypothetical, this study investigates issues of demand revelation, hypothetical bias, and value uncertainty for four elicitation mechanisms used in contingent valuation surveys: dichotomous choice, dichotomous choice with follow-up certainty question, payment card, and multiple-bounded discrete choice. For all elicitation mechanisms, we find no evidence of hypothetical bias: voting decisions do not vary systematically when payment is hypothetical versus when it is real. Under all design conditions we find the fewest deviations between stated and induced values and the strongest evidence of demand revelation with dichotomous choice. Stated uncertainty in dichotomous choice follow-up and multiple-bounded discrete choice questions does correlate with uncertain induced values, but the signal is noisy. We discuss the implications of our findings for the design of contingent valuation surveys.