German Aerospace Center, Stuttgart, Germany.
Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany.
PLoS One. 2019 Jan 8;14(1):e0209872. doi: 10.1371/journal.pone.0209872. eCollection 2019.
The percentage of protesters in contingent valuation surveys is substantial-about 20% across many studies. This paper seeks to clarify the motivations behind protest responses. In addition, the question whether the estimation of willingness to pay (WTP) is more biased by the exclusion or inclusion of protest bids is yet undecided. Methodological improvements are difficult for three reasons: motivations behind protest responses are largely unclear, definitions of protest differ between studies and often only participants who state a zero WTP are asked for their reasons. Our survey on farm animal welfare (n = 1335) provides detailed motivations, two definitions and includes debriefing of all participants for their WTP. We find that protest bids are not a refusal to answer, they are neither irrational nor driven by lack of understanding. Quite the contrary, a large part of participants is directly motivated by moral reasons. Furthermore, protest responses are not coupled to a zero WTP. In our sample, only 8% out of 32% protesting participants had a zero WTP. Only a small fraction of zero bids (0.4%) are true WTP-statements, i.e. respondents were satisfied with the status quo. This finding has important implications for existing WTP-estimates which might be biased. Finally, we provide detailed estimates of the WTP for animal welfare issues by including and excluding different types of protesters and outliers.
在意愿调查评估中，抗议者的比例相当大——在许多研究中约占 20%。本文旨在厘清抗议回应背后的动机。此外，关于排除或纳入抗议出价是否会更偏向于支付意愿（WTP）的估计，这一问题仍未得到解决。出于三个原因，方法论的改进较为困难：抗议回应背后的动机在很大程度上并不明确；不同研究对抗议的定义不同，而且往往只要求那些表示零 WTP 的参与者说明其原因。我们关于农场动物福利的调查（n=1335）提供了详细的动机、两种定义，并对所有参与者的 WTP 进行了事后解释。我们发现，抗议出价不是拒绝回答，它们既不是非理性的，也不是由于缺乏理解所致。恰恰相反，很大一部分参与者是出于道德原因直接受到激励。此外，抗议回应与零 WTP 无关。在我们的样本中，只有 8%的 32%抗议参与者的 WTP 为零。只有一小部分零出价（0.4%）是真正的 WTP 声明，即受访者对现状感到满意。这一发现对现有 WTP 估计可能存在偏差的情况具有重要意义。最后，我们通过纳入和排除不同类型的抗议者和异常值，提供了关于动物福利问题 WTP 的详细估计。
