Mixed logit estimation of willingness to pay distributions: a comparison of models in preference and WTP space using data from a health-related choice experiment

Different approaches to modelling the distribution of WTP are compared using stated preference data on Tanzanian Clinical Officers’ job choices and mixed logit models. The standard approach of specifying the distributions of the coefficients and deriving WTP as the ratio of two coefficients (estimation in preference space) is compared to specifying the distributions for WTP directly at the estimation stage (estimation in WTP space). The models in preference space fit the data better than the corresponding models in WTP space although the difference between the best fitting models in the two estimation regimes is minimal. Moreover, the willingness to pay estimates derived from the preference space models turn out to be very high for many of the job attributes. The results suggest that sensitivity testing using a variety of model specifications, including estimation in WTP space, is recommended when using mixed logit models to estimate willingness to pay distributions.     

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.     

Distributional Preferences and the Incidence of Costs and Benefits in Climate Change Policy

We explore the relationship between willingness to pay (WTP) for climate change mitigation and distributional preferences, by which we mean individuals’ opinions about who should be responsible for climate change prevention and whether the share of climate change impacts borne by the poor is a cause for concern. We use 1,770 responses to an online stated preference survey. The domestic costs in our survey’s policy choice scenarios are expressed as a set of randomized shares across four different payment vehicles, and the international cost shares are randomized across four groups of countries. We also elicit respondents’ perceptions of the likely regressivity of climate change impacts under a policy of business-as-usual. WTP is higher when larger cost shares are borne by parties deemed to bear a greater responsibility for mitigation, and when respondents believe (and care) that the impacts of climate change may be borne disproportionately by the world’s poor. That WTP for an environmental policy depends on the distributional consequences of the policy is an unsettling result: efficiency assessments are typically assumed to be separate from equity considerations in most benefit-cost analyses.     

Demand-side factors in optimal land conservation choice

The dominant paradigm of conservation-reserve planning in economics is to optimize the provision of physical conservation benefits given a budget constraint, implicitly assuming the value of biodiversity and ecosystem function is not affected by human proximity to that natural capital. There is evidence, however, that human willingness to pay (WTP) for conservation declines with distance—a phenomenon we call “spatial value decay”. This paper begins a new strand of the conservation planning literature that takes demand-side factors – location of people in the landscape, the degree to which WTP for conservation depends on proximity – into account. We use theoretical models of linear abstract landscapes to explore the impact of demand-side factors on two facets of conservation choices: siting of a single reserve when conservation potential is greatest near a critical site, and siting of multiple reserves when fragmentation reduces physical conservation services produced. Our results show how planners should sometimes employ increased fragmentation to capture value when people's preferences are not very highly localized, and how optimal policy balances proximity to the ecologically critical site with proximity to people. In some scenarios, the payoff to using a reserve design approach that considers demand-side factors is large, but we find that spatial value decay reduces the benefits that can be gained from any conservation-planning approach.     

External Tests of Scope and Embedding in Stated Preference Choice Experiments: An Application to Endangered Species Valuation

A criticism often levied against stated preference (SP) valuation results is that they sometimes do not display sensitivity to differences in the magnitude or scope of the good being valued. In this study, we test the sensitivity of preferences for several proposed expanded protection programs that would protect up to three US Endangered Species Act-listed species: the Puget Sound Chinook salmon, the smalltooth sawfish, and the Hawaiian monk seal. An external scope test is employed via a split-sample SP choice experiment survey to evaluate whether there is a significant difference in willingness to pay (WTP) for protecting more species and/or achieving greater improvements in the status of the species. The majority of 46 scope tests indicate sensitivity to scope, and the pattern of scope test failures is consistent with diminishing marginal utility with respect to the amount of protection to each species. Further tests suggest WTP may be proportional to the number of species valued.     

A proactive approach for assessing alternative management programs for an invasive alien pollinator species

Most evaluations of the economic impacts of invasive species are done post facto and concentrate on direct production loss caused. However, the effects of invasive species on non-market services such as biodiversity and landscapes can be considerable. A proactive approach of assessing the expected economic impact of invasive species prior to their occurrence may contribute to greater efficiency of policy makers. Here we used a stated preference method for a priori evaluating the willingness of the population to pay for different control programs of a new invasive bee species in Israel, the dwarf honey bee, Apis florea. We evaluated possible economic impacts of A. florea using two model plant species expected to be adversely affected by its invasion due to decreased pollination. The plants have no market value but they add aesthetic value to the open landscape. Using a mixed logit model we found that the mean willingness to pay (WTP) differed between the model plants, and increased with the extent of plant loss. Respondents differentiated between levels of damage to the plants and between control methods in their preferences for a specific program. Our results provide means for informed proactive decision making in preventing the continued invasion of the bee.     

Willingness to pay for other species' well-being

Benefit-cost analysis of environmental policies typically focuses on benefits to human health and well-being. For other species, economists have attempted to measure human WTP for changes in the numbers of individuals for different types of wildlife, and to preserve biodiversity. When it comes to humans' WTP for improvements in the quality-of-life for other species, however, the evidence is limited. Morbidity and quality-of-life considerations may be particularly important to the task of valuing non-fatal harm to wildlife in the wake of an environmental disaster. We argue that the other species morbidity-reduction component of WTP should be calculated net of any “outrage” component associated with the cause of the harm. This net WTP is likely to be correlated with the premium that people are willing to pay for chicken products from birds for which the quality-of-life has been enhanced by improved animal welfare measures. This paper uses a conjoint choice stated preference survey to reveal the nature of systematic heterogeneity in preferences for “humanely raised” versus “conventionally raised” chicken. We also use latent class analysis to distinguish between two classes of people—those who are willing to pay a premium for humanely raised chicken, and those who are not.     

Anchors,endorsements, and preferences: A field experiment

This study investigates how access to political endorsements affects stated preferences for an environmental public good in Switzerland. We developed a contingent valuation survey questionnaire with two valuation questions, the first formulated as a (hypothetical) policy referendum, the second an open-ended WTP question. For the referendum question we solicited endorsements from a range of political parties and relevant interest groups. We then conducted a split-sample mail-survey experiment in which a table listing the endorsements was included with a subsample of the questionnaires. Access to the policy endorsements significantly affected the responses to the open-ended willingness-to-pay question.     

Temporal stability of preferences and willingness to pay for natural areas in choice experiments: A test–retest

The main objective of this paper is to test the temporal stability of stated preferences and willingness to pay (WTP) values from a Choice Experiment (CE) in a test–retest. The same group of participants was asked the same choice tasks in an internet-based CE, conducted twice with a time interval of one year without interviewer interference. We examine choice consistency at individual choice task level and transferability of the underlying indirect utility function and associated WTP values. The results show that choices are consistent in 57 percent of the choice occasions. Comparison of the choice models over time shows that the estimated preference and scale parameters are significantly different, suggesting that choice behaviour changed between the two surveys. Differences between marginal WTP estimates for individual choice attributes are statistically significant only at the 10 percent level. However, we show that this can result in significantly different WTP values for policy scenarios. The instability of estimated mean WTP values for different policy scenarios asks for caution when including WTP values in cost-benefit analysis.     

Latent preferences and valuation of wetland ecosystem restoration

We employ a latent class choice model to evaluate the effects of alternative ecological characterizations of wetland functions and services on individual preferences, and to determine whether socioeconomic factors and psychometric measures of environmental attitudes can explain differences in individual's preferences and values for wetland restoration. This analysis combines a multiattribute choice model with information on individual's characteristics to evaluate preferences for restoration of the Greater Everglades ecosystem, one of the largest and most comprehensive wetland ecosystem restoration projects. To identify potential endpoints for Everglades restoration, two alternative ecological characterizations of the ecosystem were developed using the familiar distinction between function and structure. Survey data from a representative sample of the general population were used in a split-sample design based on the ecological characterization treatment. Within each subsample, the latent class analysis identified three groups who varied in their preferences for ecosystem restoration and socioeconomic profiles. The ecological characterizations had a significant influence on respondents' preferences and willingness to pay (WTP). The subsample responding to the structural characterization had a significantly larger share of respondents in the group who favored proposed restoration plans than the functional attribute subsample. In both subsamples, the group who favored restoration had a higher WTP for restoration than other groups. The latent class analysis also revealed socioeconomic and attitudinal factors that explain some of the heterogeneity in preferences and WTP within each subsample; this heterogeneity would not be identified with a standard choice model. In the context of Everglades restoration, the results provide a baseline assessment of public support and WTP that suggests an emphasis on structural rather than functional restoration endpoints. The approach described in this article can be used in other policy studies of wetland ecosystems because multiple ecosystem services can be represented within a stated choice survey and differences in preferences and values for these services can be measured.     

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.     

Choke Price Bias in Choice Experiments

This paper reports on the results from a split sample choice experiment, where the effect of changing the maximum level of the cost attribute is investigated. The hypothesis was that changing the maximum price level would either give rise to an income effect or have no effect on consumers’ preferences. This was tested in the framework of a valuation study of different quality characteristics of minced pork. The data was analysed using a mixed logit error component model, which accounts for correlation in the unobserved part of the utility. Results suggest that the size of the maximum price level does matter, and that changing the maximum price level has a statistically significant effect on both the general preferences structure and the WTP estimates. Hence, researchers should be very careful when defining not only the range of the price attribute but also the maximum level of the price attribute.     

Exploring the shelf-life of travel cost methods of valuing recreation for benefits transfer

This study tests the stability of willingness to pay (WTP) for recreational fishing over two decades based on three rounds of a representative angler survey conducted in New York State in 1988, 1996, and 2007. We employ the travel cost method (TCM) by using the repeated conditional logit and mixed logit models to estimate demand for daily fishing trips. Our estimates suggest that anglers’ WTP for fishing in 1988 and 1996 were similar, with values per trip at $35.2 and $36.4, respectively. However, there was a noticeable decrease in WTP, to $30.6, in 2007. This decrease is consistent with two salient features of the 2007 survey: (1) long-distance trips, such as those to the Great Lakes were less frequent, and (2) anglers were, on average, older than in previous surveys.     

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.     

Spatial discounting of ecosystem services

The impact of conservation efforts targeted at preserving ecosystem services largely depend on the welfare implications associated with spatial variations in the provision of ecosystem services. While there is ample empirical evidence of spatial discounting or decay of the valuation of ecosystem services, there are still few underpinnings based on welfare economic theory. We establish a theory of spatial discounting that closely follows the concept of time discounting pertaining to climate change, and show spatial discount rates in the consumption, ecosystem service, and willingness to pay (WTP) numeraires. We consider the role of key parameters such as pure rate of spatial preference, consumption change, ecosystem services change, population density, and elasticity of marginal utility. We find that the spatial discount rate of WTP for ecosystem services that frequently appears in the empirical literature is the difference between the ecosystem service discount rate and consumption discount rate, where the ecosystem service discount rate includes both physical distance decay and welfare effects. Finally, we use numerical simulations to illustrate how the three different spatial discount rates vary with the spatial distance from the source of ecosystem services and with consumption patterns, implying many more possible spatial variations of WTP.     

Enhanced Geospatial Validity for Meta-analysis and Environmental Benefit Transfer: An Application to Water Quality Improvements

Meta-regression models are commonly used within benefit transfer to estimate willingness to pay (WTP) for environmental quality improvements. Theory suggests that these estimates should be sensitive to geospatial factors including resource scale, market extent, and the availability of substitutes and complements. Valuation meta-regression models addressing the quantity of non-market commodities sometimes incorporate spatial variables that proxy for a subset of these effects. However, meta-analyses of WTP for environmental quality generally omit geospatial factors such as these, leading to benefit transfers that are invariant to these factors. This paper reports on a meta-regression model for water quality benefit transfer that incorporates spatially explicit factors predicted by theory to influence WTP. The metadata are drawn from stated preference studies that estimate per household WTP for water quality changes in United States water bodies, and combine primary study information with extensive geospatial data from external sources. Results find that geospatial variables are associated with significant WTP variations as predicted by theory, and that inclusion of these variables reduces transfer errors.     

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.     

Understanding environmental policy preferences: New evidence from Brazil

We examine the relationship between socio-economic factors and public opinion on environmental policies in Brazil, drawing on a survey conducted in June 2012. There are few systematic studies of the determinants of environmental preferences in emerging economies, and Brazil is a particularly interesting case because of its democratic political system, rapid economic growth, and importance for the global environment. In general, we find that the Brazilian public is highly supportive of environmental protection. To explain variation in environmental preferences, we focus on the effects of income and education. Many previous studies suggest that both should have positive effects, but the empirical evidence is mixed. Indeed, we find that income has no effect on environmental preferences. However, education is a strong predictor of environmental preferences. While college education is not necessary for environmental awareness, there is a large difference between Brazilians with primary and secondary education. For policy, the findings imply that investment in secondary education can raise environmental awareness, regardless of income levels.     

Quantifying landscape externalities of renewable energy development: Implications of attribute cut-offs in choice experiments

Renewable energy is worldwide seen as a key element necessary to address climate change. However, finding socially acceptable locations for renewable energy facilities and the accompanying infrastructure increasingly often faces fierce opposition. This paper quantifies the landscape externalities of renewable energies employing a choice experiment. In addition, it is investigated how accounting for non-compensatory choice behavior, i.e. attribute cut-offs, affects welfare measures and subsequently policy recommendations. The empirical application is Germany where we conducted a nationwide survey on the development of renewable energies. We first show that cut-off elicitation questions prior to the choice experiment at least partially influence preferences. We further find that most participants state cut-off levels for attributes. Many are, however, at the same time willing to violate the self-imposed thresholds when choosing among the alternatives. To account for this effect, stated cut-offs are incorporated into a mixed logit model following the soft cut-off approach. Model results indicate substantial taste heterogeneity in preferences and in the use of cutoffs. Also, welfare estimates are substantially affected. We conclude that welfare changes from renewable energy development could be strongly underestimated when cut-offs are ignored.     

Recreation demand estimation and valuation in spatially connected systems

Recreation demand models frequently are used to explain outdoor recreation behavior and to estimate willingness to pay for changes in environmental quality at recreation sites. Among the most commonly used recreation demand models are site choice models based on the multinomial logit framework, which account for the spatial relationships between each recreator's home and multiple alternative destinations thereby capturing the substitution possibilities among recreation sites. However, standard applications of this framework typically do not account for the possibility of spatial connections among the sites via movements of the target species, such as fish in connected water bodies in recreational angling applications or terrestrial species in hunting or wildlife viewing applications. In this paper we examine aspects of environmental valuation and natural resource dynamics that generally are addressed separately. Specifically, we show that in such spatially connected systems, a “reduced form” application of the standard site choice modeling approach, using proxy measures of environmental quality rather than direct measures of species abundances, can produce biased estimates of willingness to pay for environmental improvements. Furthermore, we show that under some conditions poorly targeted environmental improvements in spatially connected systems can lead to welfare decreases. In such systems a structural model of recreator site choices and species sorting behavior and population dynamics may be required to fully account for the spatial linkages among sites and the feedback effects between recreators and the target species.