Are Internet surveys an alternative to face-to-face interviews in contingent valuation?

Internet is an increasingly popular data collection mode for stated preference research in environmental economics. However, little is known about how this survey mode may influence data quality and welfare estimates. As part of a national contingent valuation (CV) survey estimating willingness to pay (WTP) for biodiversity protection plans, we assign two groups of respondents either to an Internet or face-to-face (in-home) interview mode. Our design aims to better isolate measurement effects from sample composition effects by drawing both samples from the same sample frame. We find little evidence of social desirability bias in the interview setting or satisficing (shortcutting the response process) in the Internet survey. The share of “don't knows”, zeros and protest responses to the WTP question with a payment card is very similar between modes and equality of mean WTP cannot be rejected. Results are fairly encouraging for the use of Internet in CV as stated preferences do not seem to be significantly different or biased compared to face-to-face interviews.     

Does Question Format Matter? Valuing an Endangered Species

A three-way treatment design is used to compare contingent valuation response formats. Respondents are asked to value an endangered species (the red-cockaded woodpecker) and the restoration of its habitat following a natural disaster. For three question formats (open-ended, payment card, and double-bounded dichotomous choice), differences in survey response rates, item non-response rates, and protest bids are examined. Bootstrap techniques are used to compare means across formats and to explore differences in willingness to pay (WTP) distribution functions. Convergent validity is found in a comparison of mean WTP values, although some differences are apparent in the cumulative distribution functions. Differences across formats are also identified in item non-response rates and proportion of protest bids. Overall, the payment card format exhibits desirable properties relative to the other two formats.     

Protesting and Justifying: A Latent Class Model for Contingent Valuation with Attitudinal Data

This article develops a latent class model for estimating willingness-to-pay (WTP) for public goods using simultaneously contingent valuation (CV) and attitudinal data to identify individuals with similar characteristics, such as WTP and protest attitudes. We find evidence that the answer to the CV question influences the responses to the attitudinal questions. In our case, this influence reflects rational behavior (budget constraint issues) and justification biases related to protest reasons, such as lack of trust in institutions or fairness issues with respect to the distribution of the burden of preservation. The results from our empirical application confirm the importance of accounting for those biases.     

A Meta-study Investigating the Sources of Protest Behaviour in Stated Preference Surveys

It is a well-known empirical finding that some percentage of respondents participating in Stated Preference surveys will not give responses that reflect their true preferences. One reason is protest behaviour. If the distribution of protest responses is not independent of respondent or survey characteristics, then simply expelling protesters from surveys can lead to sample selection bias. Furthermore, WTP estimates will not be comparable across surveys. This paper seeks to explore potential causes of protest behaviour through a meta-study based on full datasets from 38 different surveys. The objective of the study is to examine the effect of respondent specific variables as well as survey specific variables on protest behaviour. Our results suggest that some of the differences in WTP typically observed between different demographic groups, different elicitation formats and different question formats might actually be attributed to inherent differences in the propensity to protest. Our results indicate that the propensity for respondents to exhibit protest behaviour when asked a stated preference type valuation question depends on a number of specific factors, respondent specific as well as survey specific—knowledge which could be used in order to reduce protest behaviour.     

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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Subject pool effects among the general population and students: a choice experiment example

Rising costs of conducting research coupled with limited budgets are forcing researchers to use samples of convenience. Students represent one such sample, but are students an appropriate population? The objective is to ascertain how students’ willingness to pay (WTP) differs from the general public’s WTP. Students and county residents are surveyed. Results suggest the study’s goal may determine if student responses are generalizable to the general population. The samples are similar in many characteristics, but WTP amounts vary. The student samples show some inconsistencies. If the goal is general behavioural inferences, the results provide support for the use of students. If the goal is to estimate specific WTPs for use in policy analysis, the use of students may not be advisable.     

Does “No” mean “No”? A protest methodology

In this paper, we propose a method of identifying and truncating protesters in Contingent Valuation surveys. We propose using a system of Willingness to Pay (WTP) questions that value multiple goods and that use both discrete choice and open-ended questions coupled with multiple questions about protest beliefs administered to the entire sample. Protesters can then be identified because they reject all bids, declare zero on all open-ended questions, and hold protest beliefs. The proposed procedure has been empirically tested on an air pollution data set from Poland, where 27 of the sample was identified as protesters. The adjustment for protesters increased the estimated WTP values by a factor of more than 3.

Choosing Between Internet and Mail Survey Modes for Choice Experiment Surveys Considering Non-Market Goods

In a choice experiment setup considering a non-market good, this paper adds to the literature on survey mode effects by providing evidence that internet surveys can be a viable alternative to traditional mail surveys when gathering feedback from a sample of respondents. The case study concerns preferences for protecting different types of landscape from road encroachment when building new motorways in Denmark. Two samples of respondents are surveyed—one by internet and one by mail. The performances of the two samples are compared over six different criteria; response rates, protest responses, demographics, preferences and WTP, estimation precision, and, finally, certainty in choice. Differences are observed for some of these criteria, implying that analysts should be aware that choosing internet over mail could be accompanied by a survey mode effect. However, the observed differences do not translate into significant differences in the unconditional WTP estimates. In most applied economic valuation studies of non-market goods, the main objective is in fact estimation of WTP. Hence, in the present case, the identified survey mode effects do not severely invalidate the applicability and continued use of the internet as a suitable means of collecting data for choice experiment economic valuation of non-market goods.     

Economic Valuation of Environmental Damages due to the Prestige Oil Spill in Spain

This paper presents a parametric and non-parametric analysis of data from a contingent valuation study (CVM) conducted to estimate environmental use and passive use losses due to the Prestige oil spill. This is the first CVM study conducted in Europe after a large oil spill. The CVM survey was implemented using in person interviews. Mean willingness to pay (WTP) values were computed with both, a parametric and non-parametric approach. Parametric WTP estimation indicates that respondents in the sample are willing to pay about 40.51 € per household to avoid a similar future oil spill in Spain. This implies that on average, the Spanish society places a value of the environmental losses caused by the Prestige oil spill around 574 € million. Non-parametric estimates are slightly higher at 58.08 € per household. WTP results are similar to those obtained in the Exxon Valdez study.     

The social acceptability and valuation of recycled water in Crete: A study of consumers' and farmers' attitudes

This paper investigates the Willingness to Use (WTU) and Willingness to Pay (WTP) for recycled water in agriculture. We report results from surveys of farmers and consumers on the island of Crete, Greece. Crete is suffering from an increasingly severe water shortage coupled with declining groundwater supplies, therefore the wider use of recycled water is an important policy priority. We have investigated WTU and WTP for two crops with two different levels of water treatment. The mean WTP for 1 cm³ of recycled water was 0.15€ for the irrigation of both olive trees and tomato crops, namely 55% of the fresh water price. The mean WTP for olive oil produced from olive trees irrigated with recycled water was 2.65€, namely 88% of its current market price. We have found that both attitudinal factors, such as environmental awareness and economic factors, such as freshwater prices and incomes, are significant in explaining the WTU and WTP for recycled water and products produced using it, but that important differences exist between farmers and consumers.     

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.     

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%.     

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.     

Marginal WTP and Distance Decay: The Role of ‘Protest’ and ‘True Zero’ Responses in the Economic Valuation of Recreational Water Quality

We evaluate the sensitivity of distance decay in individuals’ stated willingness to pay (WTP) for water quality improvements in eutrophied lakes. We extend the standard model of contingent valuation (CV) by allowing individuals to adopt a sequential evaluation process consisting of two decision stages. In the first stage respondents decide whether they are ‘protesters’, have a WTP   \(=\)   ‘true zero’ or a \(\hbox {WTP}>0\) . Conditioned on a strictly positive WTP, we use Lee’s selectivity-corrected model to determine the magnitude of their WTP in the second stage. Using CV survey data from Norway we find significant distance decay in the first stage classification of respondents as ‘protesters’, ‘true zero’ WTP, or positive WTP. In the second stage model for positive WTP responses, we find little or no significant relationships when correcting for selection. Results suggest that previous findings of significant distance decay in contingent valuation of lake and river water in Europe may be driven by the definition of ‘protest’ and ‘true zero’ respondents. We find that WTP for water quality may be more useful as a qualitative indicator of political support for user financed water quality measures, than as a cardinal measure of marginal utility of water quality improvements.     

环保PPP项目异质行动者网络构建研究

现有环保PPP项目多元主体研究缺乏对环境等非人类主体的关注。因此,在分析多元主体异质性基础上,引入行动者网络理论,清晰界定人类行动者和非人类行动者在环保PPP项目中的角色与地位,通过异质行动者转译,构建环保PPP项目异质行动者网络,清除异质行动者的行动障碍,实现异质行动者间的资源互补,提高环保PPP项目供给效率,为多元主体异质合作供给环保PPP项目研究提供新思路。     

Willingness to Pay to Reduce Mortality Risks: Evidence from a Three-Country Contingent Valuation Study

Valuing a change in the risk of death is a key input into the calculation of the benefits of environmental policies that save lives. Typically such risks are monetized using the Value of a Statistical Life (VSL). Since the majority of the lives saved by environmental policies are those of older persons, there has been much recent debate about whether the VSL should be lower for the elderly to reflect their fewer remaining life years. We conducted a contingent valuation survey in the UK, Italy and France designed to answer this question. The survey was administered in these three countries following a standardized protocol. Our results suggest that the VSL is €1.022 million or €2.264 million, depending on whether we use median or mean WTP. The VSL is not significantly lower for older persons, but is higher for persons who have been admitted to a hospital or emergency room for cardiovascular and respiratory problems. Income is positively and significantly associated with WTP. The income elasticities of the WTP increase gradually with income levels and are between 0.15 and 0.5 for current income levels in EU countries. We use the responses to the WTP questions to estimate the value of an extension in remaining life expectancy. The value of a loss of one year’s life expectancy is €54,000 or €163,000.     

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.     

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.     

Do environmental benefits matter? Evidence from a choice experiment among house owners in Germany

Residential buildings strongly contribute to global CO₂ emissions due to the high energy demand for electricity and heating, particularly in industrialised countries. Within the EU, decentralised heat generation is of particular relevance for future climate policy, as its emissions are not covered by the EU ETS. We conducted a choice experiment concerning energy retrofits for existing houses in Germany. In the experiment, the approximately 400 sampled house owners could either choose a modern heating system or an improved thermal insulation for their home. We used standard and mixed logit specifications to analyse the choice data. We found environmental benefits to have a significant impact on choices of heating systems. However, they played no role in terms of insulation choices. Based on the estimated mixed logit model, we further obtained willingness-to-pay (WTP) measures for CO₂ savings.