Bias related to the hypothetical setting remains controversial regarding the reliability and validity of value estimates from discrete choice experiments (DCEs). This has motivated a large body of literature to investigate approaches for mitigating hypothetical and strategic bias. Our study provides further evidence to inform this debate by testing whether a combination of ex-ante or ex-post mitigation strategies might be effective in reducing bias in DCEs. Specifically, we employ individual and multiple ex-ante reminders alongside an ex-post data treatment and analyse how their individual or joint use affects willingness to pay (WTP) estimates. The econometric analysis makes use of innovative semi-parametric logit-mixed logit in addition to the state-of-the-art mixed logit model. The empirical case study focuses on preferences for the environmental and social impacts of organic olive production. By comparing the three experimental treatments with a control treatment, we test whether ex-ante cheap talk, a reminder of the project's relative spatial extent, or a combination of both affect stated WTP. In addition, we use an ex-post data treatment to correct WTP estimates. WTP estimates of treatments related to ex-ante mitigation strategies did not differ significantly from those obtained from a control treatment with standard budget constraint reminders. However, the ex-post approach results in a significant reduction in mean WTP estimates and is used to investigate whether the observed choice inconsistencies are due to unintentional errors or strategic behaviour. We argue that ex-post mechanisms deserve greater attention and highlight the need to distinguish strategic behaviour from other sources of hypothetical bias.

中文翻译：

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在陈述的偏好研究中减轻假设和战略偏见的事前和事后措施的相对表现

关于离散选择实验 (DCE) 的价值估计的可靠性和有效性，与假设设置相关的偏差仍然存在争议。这促使大量文献研究减轻假设和战略偏见的方法。我们的研究通过测试事前或事后缓解策略的组合是否可能有效减少 DCE 的偏差，为这场辩论提供了进一步的证据。具体来说，我们在事后提醒的同时使用单独和多个事前提醒。数据处理和分析他们的个人或联合使用如何影响支付意愿 (WTP) 估计。除了最先进的混合 logit 模型外，计量经济分析还使用了创新的半参数 logit-mixed logit。实证案例研究侧重于对有机橄榄生产的环境和社会影响的偏好。通过将三种实验处理与对照处理进行比较，我们测试了事前廉价谈话、项目相对空间范围的提醒或两者的组合是否会影响陈述的 WTP。此外，我们使用事后数据处理来纠正 WTP 估计。与事前相关的处理的 WTP 估计缓解策略与通过标准预算约束提醒的控制处理获得的策略没有显着差异。然而，事后方法导致平均 WTP 估计值显着降低，并用于调查观察到的选择不一致是否是由于无意错误或战略行为造成的。我们认为事后机制值得更多关注，并强调需要将战略行为与其他假设偏差来源区分开来。