In striking a balance between attracting more product reviews versus maintaining review quality, online platforms have started to label reviews with whether they are associated with verifiable purchases. This paper examines the impact of such disclosure policy on the strategic behavior of review writers and the helpfulness of verified reviews (VRs) and non-verified reviews (NVRs) for review users. We propose that the introduction of the verified purchase tag induces two competing effects for VRs, increased credibility and concerns for acquisition bias, which in turn influence the behaviors of both writers and users. By exploiting the exogenous shock resulting from a policy change on Amazon, we find that, after the disclosure, NVRs became longer in length and VRs started to contain more unique information. Surprisingly, we find strong evidence that VRs receive fewer helpfulness votes than NVRs. We further explore the underlying mechanism, namely review users' concerns about acquisition bias associated with VRs, and identify conditions under which these unexpected effects can be mitigated. Our findings generate important implications for online platforms seeking to design a more effective review ecosystem and for review writers aiming to produce more helpful content.

中文翻译：

---

当平台披露与产品评论相关的购买历史记录时会发生什么情况？


为了在吸引更多产品评论与保持评论质量之间取得平衡，在线平台已经开始标记评论，说明它们是否与可验证的购买有关。本文研究了此类披露政策对评论作者战略行为的影响，以及经过验证的评论 （VR） 和非经过验证的评论 （NVR） 对评论用户的帮助。我们建议，经过验证的购买标签的引入会引起 VR 的两种竞争效应，即增加的可信度和对获取偏差的担忧，这反过来又会影响作者和用户的行为。通过利用亚马逊政策变化带来的外生冲击，我们发现，在披露后，NVR 的长度变得更长，VR 开始包含更多独特的信息。令人惊讶的是，我们发现强有力的证据表明 VR 获得的帮助投票少于 NVR。我们进一步探讨了潜在机制，即审查用户对与 VR 相关的获取偏差的担忧，并确定可以减轻这些意外影响的条件。我们的研究结果为寻求设计更有效的评论生态系统的在线平台和旨在制作更多有用内容的评论作者产生了重要影响。