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.     

Implications of Bid Design and Willingness-To-Pay Distribution for Starting Point Bias in Double-Bounded Dichotomous Choice Contingent Valuation Surveys

We examine starting point bias in double-bounded dichotomous choice contingent valuation surveys. We investigate (1) the seriousness of the biases for the location and scale parameters of the willingness-to-pay (WTP) in the presence of starting point bias; (2) whether or not these biases depend on the distribution of WTP and on the bid design; and (3) how well a commonly used diagnostic for starting point bias—a test of the null that bid set dummies entered in the right-hand side of the WTP model are jointly equal to zero—performs under various circumstances. Monte Carlo simulations suggest that the effect of ignoring starting point bias depends on the bid design and on the true distribution of WTP. A well-balanced, symmetric bid design may result in very modest biases even when the anchoring mechanism is very strong. The power of bid set dummies in detecting starting point bias is low. They tend to account for misspecifications in the distribution assumed by the researcher for the latent WTP, rather than capturing the presence of starting point bias.     

Heterogeneous anchoring and the shift effect in iterative valuation questions

In this article, we consider starting point bias as a heterogeneous phenomenon, that is, respondents in contingent valuation surveys do not anchor in the same way. We study the consequences of a mistaken assumption of homogeneous anchoring for the analysis of the shift effect in multiple-bounded dichotomous choice format, when respondents really have heterogeneous anchoring. We show that the shift effect, generally interpreted as incentive incompatibility or “yea”-saying, can be the spurious outcome of disregarded heterogeneous anchoring.     

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.     

Application of Sample Selection Model to Double-Bounded Dichotomous Choice Contingent Valuation Studies

Modeling households' behavior with the data from a contingentvaluation (CV) survey is often complicated by samplenon-response, which can cause non-response bias and sampleselection bias, leading to inconsistent parameter estimates and adistorted mean willingness-to-pay estimate. This paper reportsthe results of empirical tests for both biases using householdsurvey data in which the double-bounded dichotomous choice CVquestion involved the benefit of a tap water quality improvementpolicy in Korea. No non-response bias, but sample selection bias,is detected in the sample. To correct for sample selection bias,a sample selection model is employed. The authors also discusshow failure to correct for bias may distort aggregate benefitestimates.     

Context effects: A representation of choices from categories

This paper studies a model of reference-dependent choice from sets of options grouped into categories. The proposed model is consistent with experimental evidence documenting context effects in a variety of choice situations. In our model, the reference point for any given category is subjective, and corresponds to the least preferred element in the category under consideration. Every object in a category is evaluated relative to the corresponding reference point; this may distort the objective ranking of options across different categories, and thus possibly give rise to a context-effects bias. The resulting representation is essentially unique. We also provide an economic application of the preferences that we axiomatize to principal-agent models. We show how sellers facing consumers exhibiting the context-effects bias can increase their profits by exploiting their bounded rationality.     

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.      

Provision Point Mechanisms and Field Validity Tests of Contingent Valuation

Past field validity tests of contingent valuation have relied on voluntary contribution mechanisms to elicit actual willingness to pay, and may overestimate hypothetical bias because of free riding in the actual contributions. This paper argues that provision point mechanisms are a preferred alternative for field validity tests of contingent valuation because they increase the proportion of demand revealed in cases in which public goods can be provided in a step function. The results of a contingent valuation validity study of participation in a green electricity pricing program that uses a provision point mechanism are reported, and hypothetical open-ended and dichotomous choice responses are compared to actual participation. Calibration of hypothetical responses is also explored.     

Evaluating the Validity of the Dichotomous Choice Question Format in Contingent Valuation

Hypothetical and actual cash willingness to pay (WTP) for an art print were elicited with dichotomous choice and open-ended question formats. Comparing hypothetical and actual dichotomous choice responses using both a likelihood ratio test and the method of convolutions suggests we reject equality at the 0.05 but not the 0.01 level. Hypothetical WTP was roughly two times actual WTP with the dichotomous choice format. There were no significant differences between the open-ended and dichotomous choice question formats when both were used to estimate hypothetical WTP or both used to estimate actual WTP.     

Hypothetical Bias in Risk Preferences as a Driver of Hypothetical Bias in Willingness to Pay: Experimental Evidence

This study provides new insight on the established issue of elicitation bias in hypothetical choice settings. In particular, using an experiment that elicits real and hypothetical willingness to pay for the protection of otters, we provide evidence that the observed bias is driven by those who are both uncertain about their value and exhibit hypothetical bias in risk attitudes. This finding provides a reason why calibration approaches based on follow-up certainty questions have proven useful, but also suggests a degree of caution in applying the approach. Our results favour combining uncertainty calibration with CVM-X in which hypothetical bias in risk attitudes is also taken account to correct for hypothetical bias in WTP.     

Self-selection bias in estimated wage premiums for earnings risk

This note develops a simple occupational choice model to examine three types of selection biases that may occur in empirically estimating the premium for uncertain wages. Individuals may select themselves into risky (wage-uncertain) jobs because they have (1) lower risk aversion, or (2) lower income risks, or (3) higher individual ability. We show that (1) gives no bias, (2) biases the OLS estimate of the risk-premium in a wage regression upward, and (3) yields a bias that analytically may be positive or negative, but empirically is more likely to be negative if our occupational choice model is correct.     

Contingent valuation and actual payment for voluntarily provided passive-use values: Assessing the effect of an induced truth-telling mechanism and elicitation formats

A fundamental question about the contingent valuation (CV) method is to what degree it predicts actual payments (AP). This has particularly been an intriguing matter related to voluntary provision of public goods representing primarily passive-use values. This paper reports the results from such a CV–AP comparison. Applying a voluntary payment mechanism there exists a theoretical expectation of upward bias in CV estimates and downward bias in AP. This study applied an induced truth-telling mechanism in one treatment group to assess the hypothetical bias effect in CV. The CV estimates in this treatment group were significantly lower than in the group that did not face this mechanism. But this effect was limited to those responding/acting to dichotomous choice, not affecting those responding to open-ended questions about willingness to pay.     

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.     

Dealing with internal inconsistency in double-bounded dichotomous choice: an application to community-based health insurance

Contingent valuation method is commonly used in the field of health economics in an attempt to help policy makers in their policy-making decision process. The use of the double-bounded dichotomous choice format results in a substantial gain in statistical efficiency over the single-bounded dichotomous choice format. Yet, there is internal inconsistency with a downward mean shifting in the second responses. Using data from a community-based health insurance survey, this paper aims at testing whether double certainty calibration reduces internal inconsistency in a double-bounded dichotomous choice contingent valuation survey. Results suggest that double calibration significantly reduces internal inconsistency while maintaining the efficiency gain arising from the double-bounded format.     

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.     

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.     

The impossibility of rational consumer choice

In this paper we show that a rational consumer choice along the lines traditionally suggested might lead to paradoxical results if one considers multidimensional goods, which incorporate a series of incommensurable aspects. Thereby, we explore the similarity between the resulting paradox and Kenneth Arrow’s well known Impossibility Theorem. Based on these considerations we suggest a solution for the former problem along the lines of Herbert Simon and Amos Tversky, which might—if driven to its extreme—even provide a unique and arguably rational solution for consumer choice among multidimensional goods. Eventually, we argue that the resulting framework poses a potentially useful starting point for further developing an evolutionary theory of consumer choice.     

An Experimental Testing of Anchoring Effects in Discrete Choice Questions

This paper re-examines the openended/dichotomous choice question in the lab. It hasearlier been suggested that the dichotomous choiceformat suffers from anchoring and yea-saying.Comparing actual economic commitments for a privategood with a significant market value, we cannot rejectthe null hypothesis of equal WTP for the two formats.We conclude that problems with DC might be due toissues of how the survey is framed, not the DCquestion itself.     

On the user cost and homeownership

This paper studies the differences in the cost of housing services for renters and homeowners and calculates the bias that results when we value owner-occupied housing services using a rental equivalence approach. Our framework is a life-cycle model with endogenous tenure choice with households facing idiosyncratic uninsurable earnings risk and housing price risk. We model houses as illiquid assets that provide collateral for loans. To analyze the impact of preferential housing taxation on the tenure choice and the bias, we consider a tax system that mimics that of the US economy. Namely, owner-occupied housing services are not taxed and mortgage interest payments are deductible. Through simulations, we show that a rental equivalence approach (relative to a user cost approach) overestimates the cost of housing services. The magnitude of the bias is very sensitive to both the income tax rate and the size of adjustment costs in the housing market.     

Cost credibility and the stated preference analysis of public goods

Two recent stated preference studies include questions that explore participants’ beliefs regarding the cost amount stated in the valuation question in relation to the cost to them if the project were implemented. Results from these studies suggest that a significant proportion of people do not believe these stated cost amounts. This paper explores the implications of participants answering valuation questions that are not consistent with their beliefs regarding stated costs. As an example, the paper develops a response model for dichotomous choice stated preference questions. Participants gather project information through the stated preference experiment, form a prior distribution of costs, update the distribution of costs based on a survey's stated cost and then respond to the dichotomous choice stated preference question. The model suggests that participants will not generally respond truthfully in the sense that they may say no to a stated cost that is less than their willingness to pay for a project or yes to a stated cost that is more than their willingness to pay. While the model findings suggest potentially serious problems with stated preference estimation, the observed patterns of disbelief from the empirical studies result in downwardly biased estimates of mean willingness to pay.