خویشتن بینی و ارزیابی محصولات اخلاقی: بیان در مقابل تمایل واقعی به پرداخت

Hypothetical bias in stated-preference methods appears sometimes to be very large, and other times non-existent. This is here largely explained by a model where people derive utility from a positive self-image associated with morally commendable behavior. The results of a choice experiment are consistent with the predictions of this model; the hypothetical marginal willingness to pay (MWTP) for a moral good (contributions to a WWF project) is significantly higher than the corresponding real-money MWTP, whereas no hypothetical bias is seen for an amoral good (a restaurant voucher). Moreover, the evidence suggests that also the real-money MWTP for the moral good is biased upwards, in the sense that it appears to be higher within than outside the experimental context.

What determines people's responses in stated-preference (SP) surveys that target issues with a perceived ethical dimension, such as valuation of environmental and various other types of public goods? And to what extent can we interpret those responses as being representative of underlying preferences? These questions are crucial from a policy perspective, in particular in the US and an increasing number of European countries, where cost-benefit analysis, often making use of SP methods, is compulsory for all major proposed regulations. Although most researchers probably agree that there is potential scope for overstatement in various kinds of SP studies, no consensus exists on whether this is a major problem, or on how hypothetical estimates could or should be calibrated to better represent underlying preferences. Perhaps more importantly, few studies have investigated for which types of goods and under what circumstances hypothetical bias is likely to occur, and why this is the case. In this paper, we develop and test a theoretical model aimed at explaining variations of hypothetical bias in the literature. Drawing on papers by Andreoni, 1989 and Andreoni, 1990, Kahneman and Knetsch (1992), Akerlof and Kranton (2000), Brekke et al. (2003), Santos-Pinto and Sobel (2005), and Nyborg and Brekke (2010), the model proposes that people, in addition to the instrumental benefits associated with a good, derive utility from a positive self-image. This, in turn, is influenced by (i) the degree to which stated or real behavior coincides with the respondents’ ethical views, and (ii) the extent to which respondents are honest with themselves. The model predicts that in SP studies people overstate their marginal willingness to pay (MWTP) for goods with a perceived ethical dimension, denoted moral goods, but not for morally neutral goods. The model furthermore suggests that also the elicited real-money MWTP exaggerates people's valuation of a moral good, although to a lesser extent. In order to test these predictions, we conduct a choice experiment (CE) assessing people's valuation of what we refer to as a moral and an amoral good, respectively. A CE is an SP method where the respondents make repeated choices between bundles of goods. The method has been increasingly used to value non-market goods (see, e.g., Louviere et al., 2000 and List et al., 2006). The moral good is here represented by a donation to a campaign administered by the World Wildlife Fund (WWF) to help save the Asian Elephant, and the amoral good is a voucher valid at a local Italian restaurant in Gothenburg, Sweden. The CE is then compared with the outcome of a similar exercise, based on another but similar sample drawn from the same underlying student population, only this time using real instead of hypothetical monetary trade-offs. The empirical results are consistent with the predictions of our model; the stated MWTP for the moral good (the WWF campaign) is significantly higher than the corresponding real-money MWTP, whereas no difference is found between stated and real-money WTP for the amoral good (the restaurant voucher). In following up on these findings, we illustrate how also the real-money CE exaggerates people's valuation of the moral good, in the sense that the experimental situation per se seems to induce a positive bias. Section 2 presents a brief review of hypothetical bias in SP studies and of relevant psychological and behavioral economics literature that helps to explain past empirical results. Section 3 presents a formalized model and derives testable hypotheses, whereas Section 4 outlines the CE design for assessing the value of our moral and amoral good. The empirical results are presented in Section 5, while Section 6 discusses the findings in a broader context.

It is often argued in the environmental valuation literature that people will reveal their true preferences unless they have a strategic incentive not to do so. However, as argued by Cummings et al. (1997), such “epsilon truthfulness” is a very strong assumption for which there is not much empirical support. Indeed, a frequent criticism of SP methods is that, due to their hypothetical nature, such approaches are likely to result in overestimation of the true values people place on public goods. However, the empirical results of such tests differ, and from several reviewed meta-studies it appears far from correct to conclude that hypothetical survey methods always overstate the benefits of public goods. As far as we know, the model developed here is the first aimed at explaining the observed variation of hypothetical bias across studies. It is also, to our knowledge, the first attempt to test differences between hypothetical and real-money WTP for public and private goods within the same experimental context. The central tenet of our model is that people derive utility from a positive self-image, which depends on the degree to which they act in accordance with their ethical beliefs and how honest they are to themselves. Thus, people have an incentive, through self-deception and/or self-signaling, to overstate their true MWTPs if a high value is in accordance with their ethical views, but not otherwise. In other words, there is a positive hypothetical bias for what is here denoted moral goods, but no such hypothetical bias for amoral goods. The empirical results presented in this paper are consistent with these hypotheses, and inconsistent with the conventional model typically assumed in the environmental valuation literature; the hypothetical MWTP is significantly higher than the real-money MWTP for a public good with moral implications, whereas no such difference is found for a private, morally neutral good. Another hypothesis derived from our model is that even real-money CEs tend to exaggerate people's valuations of moral goods. This was shown to be consistent with our experimental results combined with a straightforward thought experiment, and it is also in line with doubts expressed by List et al. (2004), List (2007), and Levitt and List (2007) about whether real-money experiments really measure correctly the magnitudes of people's true preferences outside the experimental situation.16 The model also corresponds with important psychological insights as well as recent findings in the behavioral and experimental economics literature. It draws upon well-established arguments that attitudinal statements and actions not only reflect instrumental motives, but also rest on presentational concerns and underlying ideals toward which a person aspires. Yet, the fact that the model presented here is consistent with the experimental results and also is in line with insights from much psychological research does of course not mean that the model is necessarily the correct one, since there may be other models that are able to explain the experimental results here. That attitudes and actions partly represent symbolic expressions raises some questions about what should and should not be accounted for in a benefit assessment. Some authors have argued that it is irrelevant whether people's preferences reflect selfish interests, instrumental considerations, moral judgments, or any other reasons for that matter, hence suggesting that all such value foundations are valid. Yet, a major problem arises for public policy analysis if these motivations are context specific and do not transcend from one situation to another. It is arguably important to analyze various kinds of unselfish behavior experimentally. People are clearly not as selfish as the standard Homo economicus model suggests. Yet, people may sometimes not be as unselfish or altruistic in a day-to-day setting as some experimental findings seem to suggest either. Or they may indeed sometimes display remarkably unselfish behavior also in real life, but such behavior is often internally motivated and conditioned on the extent to which the individual herself receives credit for taking a certain action, and not on the actual consequences of the behavior per se.