Sensitivity of Willingness to Pay Estimates to the Level of Attributes in Discrete Choice Experiments

This paper considers issues raised in the application of discrete choice experiments (DCEs) to estimating willingness to pay (WTP). The main issue addressed is the sensitivity of WTP estimates to the level of attributes. A DCE, concerned with preferences for alternative cervical screening programmes, was carried out with women in the Tayside area of Scotland. A split sample design was employed in which respondents were divided into two groups. Each group received a discrete choice questionnaire that varied with respect to the levels of three of the six attributes. The price attribute was one of the attributes that varied across questionnaires. Whilst estimated coefficients were not significantly different across five of the six attributes included in the experiment, mean WTP estimates were significantly different for four of the five welfare estimates. However, from a policy point of view, such a difference may not be important. Consideration is also given to other general methodological and policy issues that are raised when using DCEs to estimate WTP. The findings suggest the need for further research into the design and application of DCEs as a method for estimating WTP.     

Choice Consistency and Preference Stability in Test-Retests of Discrete Choice Experiment and Open-Ended Willingness to Pay Elicitation Formats

This study tests the temporal stability of preferences, choices and willingness to pay (WTP) values using both discrete choice experiment (DCE) and open-ended (OE) WTP elicitation formats. The same sample is surveyed three times over the course of two years using each time the same choice sets. Choice consistency is positively correlated with choice certainty and choice complexity. The impact of choice complexity fades away in time, most likely as a result of learning and preference refinement. Although the OE WTP values remain stable over a time period of 2 years as in previous stated preference studies, DCE based WTP measures differ significantly, suggesting their use in benefits transfer may be limited.     

Bayesian Conjoint Choice Designs for Measuring Willingness to Pay

In this paper, we propose a new criterion for selecting efficient conjoint choice designs when the interest is in quantifying willingness to pay (WTP). The new criterion, which we call the WTP-optimality criterion, is based on the c-optimality criterion which is often used in the optimal experimental design literature. We use a simulation study to evaluate the designs generated using the WTP-optimality criterion and discuss the design of a real-life conjoint experiment from the literature. The results show that the new criterion leads to designs that yield more precise estimates of the WTP than Bayesian D-optimal conjoint choice designs, which are increasingly being seen as the state-of-the-art designs for conjoint choice studies, and to a substantial reduction in the occurrence of unrealistically high WTP estimates.     

Addressing Negative Willingness to Pay in Dichotomous Choice Contingent Valuation

This paper has four purposes. First, we outline the controversy surroundingthe issue of negative willingness to pay (WTP)in contingent valuation (CV) studies. Second,we use Monte Carlo simulation to examine theperformance of alternative distributionalassumptions in estimating WTP in the presenceof varying proportions of the populationholding negative WTP values. We focus ondichotomous choice CV (DC-CV), where negativeWTP values may be especially difficult todetect. Third, we extend the simulation toinvestigate the performance of the mixturemodels that have recently been proposed forhandling/identifying non-positive WTP values. Fourth, we extend the simulation to investigatethe performance of the nonparametric lowerbound Turnbull approach. Results indicate thatthe relative performance of the DC-CV modelingalternatives evaluated here, which assumepositive WTP, varies across the simulationsetting (e.g., proportion of negative WTP); butnone can be said to reasonably ``solve' theproblem ex post. This underscores theimportance of ex ante efforts to identify ifnegative WTP is likely to be prominent in agiven valuation setting. In such cases,appropriately handling negative WTP must beaddressed through ex ante survey design andmodeling choices that allow negative WTP.     

Response Strategies and Learning in Discrete Choice Experiments

This study explores ordering effects and response strategies in repeated binary discrete choice experiments. Mechanism design theory and empirical evidence suggest that repeated choice tasks per respondent induce strategic behaviour. We find evidence that strategic opportunities provided by the order in which choice sets are presented to respondents affect choice decisions (strategic response). The results suggest, however, that respondents may solely respond to high cost rather than low cost inconsistencies. That is, respondents are more cost sensitive, and thus have a lower willingness to pay (WTP), if the same or a similar level of provision was offered in a previous choice set at a lower cost than if it was not. Yet, the cost sensitivity, and thus WTP, remains unaffected if the same or a similar level of provision was offered in a previous choice set at a higher cost. Our findings further indicate that cost sensitivity increases (and thus WTP decreases), when respondents progress through the choice task, with this increase (decrease) lessening as more choice questions are answered. Possible explanations are value learning and strategic learning.     

Revealing Differences in Willingness to Pay due to the Dimensionality of Stated Choice Designs: An Initial Assessment

Stated choice (SC) methods are now a widely accepted data paradigm in the study of the choice responses of agents. Their popularity has spawned an industry of applications in fields as diverse as transportation, environmental science, health economics and policy, marketing, political science and econometrics. With rare exception, empirical studies have used a single SC design, in which the numbers of attributes, alternatives, choice sets, attribute levels and ranges have been fixed across the entire design. As a consequence the opportunity to investigate the influence of design dimensionality on behavioural response has been denied. Accumulated wisdom has promoted a large number of positions on what design features are specifically challenging for respondents; and although a number of studies have assessed the influence of subsets of design dimensions, there exists no single study (that we are aware of) that has systematically varied all of the main dimensions of SC experiments. This paper reports some initial findings on what influences, in aggregate, specific design configurations have on the mean willingness to pay for specific attributes using a Design of Designs (DoD) SC experiment in which the ‘attributes’ of the design are the design dimensions themselves. The design dimensions that are varied are the number of choice sets presented, the number of alternatives in each choice set, the number of attributes per alternative, the number of levels of each attribute and the range of attribute levels. The empirical evidence, using a sample of respondents in Sydney choosing amongst trip attribute bundles for their car commuting trip, suggests that, within the boundaries of design dimensionality investigated, mean estimates of WTP for travel time savings in the aggregate cover a range that is appropriate for reporting a global mean and a set of meaningful values for sensitivity testing in project appraisal and demand prediction. When these aggregated mean estimates are conditioned on all design dimensions we do not find any systematic differences due to specific design dimensions; however when each design dimension is assessed without controlling for the other dimensions we find evidence to support differences in aggregate mean WTP attributable to the number of attributes per alternative and the number of alternatives in a choice set. Research funded under the Australian Research Council Large Grants Scheme, Grant A00103962.     

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.      

Continuous Versus Discrete Time in Dynamic Common Pool Resource Game Experiments

Environmental and Resource Economics - We study the impact of discrete versus continuous time on the behavior of agents in the context of a dynamic common pool resource game. To this purpose, we...     

Despairing Over Disparities: Explaining the Difference Between Willingness to Pay and Willingness to Accept

This paper examines the three major explanations for the disparity between willingness-to-pay (WTP) and willingness-to-accept (WTA) observed in contingent value surveys and laboratory experiments: a belief that the results must be biased in some fashion, Hanemann's (1991) substitutes hypothesis, and the loss aversion model proposed by Tversky and Kahneman (1991). Starting from the assumption that individuals make utility maximizing choices, we develop structural equations that yield parametric tests of the hypotheses within a single, non-experimental framework. The approach is flexible enough to incorporate a variety of functional form and distributional assumptions and can be applied to either data from either open-ended bids or dichotomous choice questions. The usefulness of the approach is demonstrated using data from a survey that asked both WTP and WTA questions. The results provide weak support for loss aversion.     

发展中国家的汇率制度选择

文章运用随机效应、面板数据、多元离散选择模型来分析发展中国家自布雷顿森林体系崩溃以来的汇率制度选择.文章使用模拟最大似然值方法估计了静态与动态模型.解释变量包括最优货币区原则、最优稳定化需要以及和货币危机有关的因素.文章发现,最优货币区原则对选择汇率制度有指导意义,而很多变量对中间汇率制度的影响不同于对浮动或固定汇率制度的影响.此外,汇率制度选择的较高序列相关性主要由汇率制度选择的状态依赖性引起.     

Willingness to Pay for Car Safety: Evidence from Sweden

This study estimates a marginal willingness to pay (WTP) function for a road-mortality risk reduction. Observed marginal WTP from the Swedish car market is used and found to be positively correlated with the baseline risk of the cars. No statistically significant relationships between examined owner attributes, e.g. wealth and background risk, and marginal WTP are found. When comparing the estimated monetary value of a non-marginal risk reduction derived from the integral of the marginal WTP-function with an estimate based on marginal WTP we find, in line with expectations, that the difference between the estimates is negligible for smaller risk reductions and small, 4–10%, also for relatively large risk reductions.      

Comment on “Revealing Differences in Willingness to Pay Due to the Dimensionality of Stated Choice Designs: An Initial Assessment”

There are very few studies that quantify the interactions and tradeoffs between statistical and cognitive efficiency in designing stated-choice studies. While a conceptual framework for evaluating cognitive strategies would be desirable, Hensher adopts a strictly empirical approach in this experiment. The success of the study must be evaluated in light of his aggregating attributes rather than controlling the number of attributes, asymmetry in the narrow-range and wide-range attributes, and lack of orthogonality between the number of attributes and number of alternatives. Nevertheless, Hensher challenges uncritical acceptance of any given set of design features and correctly insists that we confirm our experience with rigorous, quantitative experiments.     

Incorporating Discontinuous Preferences into the Analysis of Discrete Choice Experiments

Data from a discrete choice experiment on improvements of rural landscape attributes are used to investigate the implications of discontinuous preferences on willingness to pay estimates. Using a multinomial error component logit model, we explore differences in scale and unexplained variance between respondents with discontinuous and continuous preferences and condition taste intensities on whether or not each attribute was considered by the respondent during the evaluation of alternatives. Results suggest that significant improvements in model performance can be achieved when discontinuous preferences are accommodated in the econometric specification, and that the magnitude and robustness of the willingness to pay estimates are sensitive to discontinuous preferences.     

农户畜禽防疫服务支付意愿及其影响因素分析

基于对江苏、江西、内蒙、云南四省(区)447户的农户畜禽防疫服务调查,运用支付意愿方法,得到上述地区农户的畜禽防疫服务支付意愿,并通过Logistic回归模型对农户畜禽防疫服务支付意愿的影响因素进行了分析。研究结果表明,影响农户畜禽防疫服务支付意愿的因素除了农户家庭和生产等一些常见的特征变量外,还有农户所在社区畜禽防疫服务可及性等多方面的因素。基于这些实证研究结果,本文提出政府应增加投入,以及完善农村公共服务基础设施建设等相关政策建议。     

Variability Measurements and Choice of Exchange Rate System: Asian Versus industrialized Countries

This paper examines whether the exchange rate movements of six Asian countries and six industrialized countries are normally distributed. This study also uses stochastic dominance to determine whether risk averse investors would prefer the fixed exchange rate system to the floating exchange rate system. Our empirical results show that most exchange rate changes are non-normal stable. Results form the stochastic dominance technique indicate that not all risk averse individuals will necessarily prefer one exchange rate system to the other. [F31]     

Spatial Heterogeneity of Willingness to Pay for Forest Management

The paper investigates the spatial heterogeneity of public’s preferences for the implementation of a new country-wide forest management and protection program in Poland. Spatial econometric methods and high resolution geographical information system data related to forest characteristics are used to explain the variation in individual-specific willingness to pay (WTP) values, derived from a discrete choice experiment study. We find that respondents’ WTP is higher the closer they live to their nearest forest, and the scarcer forests are in the area where they live. Interestingly, the higher the ecological value of forests in respondents’ area, the more people prefer extending areas of national forest protection. We also investigate spatial patterns in individual-specific WTP scores and in latent class membership probabilities, finding that preferences are indeed spatially clustered. We argue that this clustering should be taken into account in forest management and policy-making.     

The Willingness to Accept Value of Statistical Life Relative to the Willingness to Pay Value: Evidence and Policy Implications

Large disparities between willingness to accept (WTA) and willingness to pay (WTP) based values of statistical life are commonly encountered in empirical studies. Standard economic theory suggests that if a public good is easily substitutable there should be no marked disparity between WTA and WTP values for the good, though the disparity increases with reduced substitutability. However, psychologists have shown that people often treat gains and losses asymmetrically and tend to require a substantially larger increase in wealth to compensate for a loss than the amount they would be willing to pay for an equivalent gain. Although most transport projects may aim to improve safety, situations arise when a relaxation of an existing regulation saves resources but increases the risk of death and injuries. A survey was recently carried out in New Zealand to determine people’s willingness to pay to reduce road risks and their willingness to accept compensation for an increase in risk. This paper reports the disparity observed between the two measures and considers some of the problems posed for policymakers.