Respondent uncertainty in a contingent market for carbon offsets

The main objective of this paper is to provide additional empirical evidence of what explains respondent uncertainty in contingent valuation (CV) and how this in turn affects stated willingness to pay (WTP). Air travelers asked to pay a carbon travel tax to offset carbon emissions from flying were asked how likely it is that they will actually pay if the tax is voluntary. When changing the market compliance imperative from a mandatory carbon tax to a voluntary contribution, a third of all air travelers consider it unlikely they will actually pay their stated WTP amount. An ordered probit estimation approach is applied to identify the sources of respondent uncertainty. Besides the bid price, respondent sense of responsibility and belief in the effectiveness of the voluntary carbon market are among the main reasons for the experienced uncertainty.     

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.     

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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Conservative dichotomous choice responses in the active policy setting: DC rejections below WTP

An important feature of a Contingent Value (CV) study is that researchers design a survey that guides respondents to answer dichotomous choice (DC) questions as if they represent once-and-for-all choices. Researchers frequently construct hypothetical markets to satisfy this condition; yet detractors assert that ‘hypotheticality’ leads inevitably to inflated DC responses. For active policy questions, however, some respondents may suspect that a CV informs an actual policy issue; so to reject a DC might induce the policy-maker to reintroduce the policy with a price reduction or a program improvement. With potential incentives to deflate a DC response when policies are active, we locate two types of respondents that represent two different incentives. One class is expected to be able to risk permanent rejection of a waiver from one automobile emissions inspection. This class more frequently rejects a DC value known to improve existing conditions. Another respondent class is expected to be risk averse to defeat of the program or to excessive delay. Predictably, these respondents more frequently accept a DC value that represents a known gain. Conservative DC responses have implications for the use of CV in active policy contexts, opening a role for theory to assist practitioners in these circumstances.      

Identifying inconsistent responses in dichotomous choice contingent valuation with follow-up questions

We develop a new but simple non-parametric method to diagnose inconsistency in double-bounded contingent valuation questions in the presence of both perfect and imperfect correlation between initial and follow-up response distributions. The proposed method can identify inconsistency in iterative responses at each bid interval. We apply this method to data from five well-known double-bounded contingent valuation surveys. The predictions of our model match closely with parametric outcomes. Further, we find that the inconsistency patterns generally vary for different data sets and different bid intervals within data sets. Therefore no single behavioral model can explain all latent inconsistency patterns either within or across data sets. In addition, we examine the impact of inconsistency in responses on bias and efficiency of the double-bounded format in the absence of correction for inconsistency. We conclude that the commonly cited benefits of the double-bounded format hold only in the special case of nearly perfect consistency between initial and follow-up response distributions. Our method provides a simple tool researchers can use to determine the similarity in response distributions between the initial and follow-up responses and whether incorporating collected follow-up responses are likely to actually increase efficiency without introducing bias.     

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.     

Incentive and informational properties of preference questions

Surveys are frequently used by businesses and governments to elicit information about the public’s preferences. They have become the most common way to gather preference information regarding goods, that are not (or are not yet) bought or sold in markets. In this paper we apply the standard neoclassical economic framework to generate predictions about how rational agents would answer such survey questions, which in turn implies how such survey data should be interpreted. In some situations, the standard economic model would be expected to have no predictive power. For situations where it does have predictive power, we compare different survey formats with respect to: (a) the information that the question itself reveals to the respondent, (b) the strategic incentives the respondent faces in answering the question, and (c) the information revealed by the respondent’s answer. Earlier versions of this paper have been presented as a plenary address to the European Association of Environmental and Resource Economics in Oslo, as an invited paper at the Japanese Forum on Environmental Valuation meeting in Kobe, and at a NOAA conference on stated preference methods.     

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.     

Willingness to pay for environmental goods in Norway: A contingent valuation study with real payment

The study seeks to determine the maximum willingness to pay (MWTP) among a random sample of Norwegians, for membership in the largest environmentalist association in Norway, Norges Naturvernforbund (NNV). The study includes three stages: (1) a contingent valuation study, testing hypothetical MWTP; (2) those whose stated MWTP is at or above the current membership fee are then asked to pay this fee; (3) those individuals who do not pay in stage 2 are interviewed, and asked to consider revising their MWTP statement. The study is seemingly the first of its kind in comparing hypothetical and actual MWTP by typing valuation of a public good (the environment) to the value of a private good (membership of the NNV). The results show a rather poor correspondence between hypothetical and actual MWTP, since only 6 out of 64 who stated that they were willing to pay the membership fee in stage 1, actually paid this voluntarily in stage 2. Possible reasons for this discrepancy are discussed, on the basis of data from the telephone interview in stage 3, and on information gathered in stage 1. The data indicate that a substantial part of this discrepancy is due to MWTP being overstated in stage 1, but that other reasons also are important.     

Costing the traffic barrier effect: A contingent valuation survey

When considering the environmental damage caused by road traffic, one traditionally focuses attention on the consequences of accidents, or on the impact of air and noise pollution. This somewhat narrow definition should be enlarged to capture other, more psychological nuisances. The barrier effect created by heavily travelled streets belongs to this group of nuisances, rarely described and never estimated in monetary terms. It particularly affects children, the disabled and elderly people for whom the street becomes too large to cross. In a survey carried out at Neuchâtel, Switzerland, a contingent market was proposed to suppress the barrier effect around the city centre. A valuation function to predict the bids is estimated and used to infer the annual cost of the nuisance.     

Combining Contingent Valuation and Choice Experiments. A Forestry Application in Spain

When many good variants are to be valued, like in several forest management programs which differ in the attribute levels, the Contingent Valuation Method may not be a practical option, given the cost and time involved to value each variant separately. There are at least three alternative procedures in such situations. One (i) is to apply an attribute based valuation method like a Choice Experiment (CE); another (ii) is to conduct a CVM and a CE exercise and estimate a joint model; a third one (iii) is to use the CVM estimates to value a base scenario, and then use the CE results to adjust the CVM estimates for any new different scenario. A numerical simulation and an empirical application to an afforestation program in Spain show that the latter is the procedure that yields closer values to the CVM estimations, followed by (ii).      

A bioeconomic model for estimating the optimal level of deer and tag sales

This paper presents a dynamic model that determines the optimal number of deer hunting permit sales, subject to the objective of maximizing the discounted economic benefits stream from both the consumptive and nonconsumptive uses of deer. This bioeconomic model integrates economic benefits estimated using the dichotomous choice contingent valuation method with biological growth constraints on deer. Using a hunting zone in California as a case study, the model found that the optimal levels of buck hunting permits sold should change on a rotational basis over time and that the current practice of not selling doe hunting permits for that zone is non optimal.     

Economic valuation of environmental services sustained by water flows in the Yaqui River Delta

We attempted to estimate the economic value of environmental services provided by restored instream flows in the water-scarce Yaqui River Delta in Mexico. The Yaqui River begins near the U.S.-Mexico border and continues for 400 km before reaching the Oviachic dam, but has not reached the nearby Gulf of California for decades due to diversions for irrigation. These diversions have degraded the riparian ecosystem, coastal wetlands, and estuaries. Environmental services provided by restored flows in the Yaqui River would include healthy riverside vegetation, wetlands and estuaries, fish and wildlife habitats, non-use values, and recreation. A contingent valuation survey in 40 neighborhoods in the most populated Delta city, Ciudad Obregon, was administered to estimate non-market values of instream uses. Respondents were given a current and hypothetical Delta scenario (the latter assumed restored water flows in the River) and asked a willingness-to-pay (WTP) question regarding purchasing water for environmental flows through higher water bills. Results from 148 in-person interviews indicated that households would pay an average of 73 pesos monthly. WTP was found related to key variables suggested by economic theory and contingent valuation studies elsewhere: income, educational level, number of children in the household, and initial bid amount. These results will allow decision makers to compare the benefits generated by different water uses, including environmental services, and to manage scarce water resources under a long-term sustainable approach.     

Contingent valuation of ill health caused by pollution: testing for context and ordering effects

Contingent valuation is being increasingly used to value episodes of ill health caused by environmental pollution. In contrast to studies that have used contingent valuation to value other types of non-market goods, health episode valuation studies have tended to 1) value several ill health episodes or symptoms in the same survey, and 2) be vague in the survey instrument about the cause of the ill health, how it would be avoided or how the improvement would be paid for. The resulting values are then combined with exposure-response functions to generate economic estimates of health damages from pollution. This study tests whether episode valuation responses are sensitive to two of these design features. In a five-country study using split sample treatments, neither episode ordering nor mention of the cause of the ill health influenced stated willingness to pay to avoid specific ill health episodes.JEL Classification: C42, I12, Q51 Correspondence to: Richard ReadyThis research was supported by the European Unions Environment and Climate Research Programme: Theme 4 - Human Dimensions of Environmental Change (contract no. ENV4-CT96-0234). Any views expressed in the paper are not necessarily the views of any of the authors employers.     

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.