EXPRESS: Are Buyers Strategic in Online B2B Reviews?
研究B2B买家是否策略性地隐瞒对高绩效供应商的评论以维持议价能力，利用中美贸易战作为自然实验发现交易量增加1单位使评论概率降低0.9个百分点，对平台信息透明度设计有启示。
While online reviews are critical in e-commerce, the strategic behavior of reviewers is understudied, especially in business-to-business (B2B) markets. We investigate buyers' strategic behaviors when leaving reviews: whether B2B buyers withhold reviews from high-performing suppliers to temper their growth and maintain future bargaining power. We collect the entire review and transaction histories of 4,605 suppliers on Alibaba.com, the largest B2B global sourcing platform, covering 62,529 reviews and 455,593 transactions from February to November in 2017 and 2018. To identify causal effects, we employ a generalized difference-in-differences approach exploiting the 2018 US-China trade war as a natural experiment. This event created a sudden and exogenous shock to supplier transaction volumes, allowing us to measure the response of non-US buyers to changes in supplier performance. We find strong evidence of strategic review withholding. A one-unit increase in a supplier's transaction volume significantly reduces a buyer's probability of leaving a review by 0.9 percentage points. We also find no effect on the numerical ratings and sentiment of reviews that are posted. This indicates that buyers respond to a supplier's success by withholding reviews, but they do not harm the seller's reputation by leaving negative reviews. This core mechanism was directly confirmed by a comprehensive survey we conducted with B2B professionals. Our findings demonstrate that B2B buyers act as strategic agents who manipulate information for competitive advantage. This presents a crucial insight for platform governance: information transparency is a double-edged sword. While intended to reduce information asymmetry, publicly disclosing performance metrics like transaction histories can enable strategic behavior that distorts the reputation system. Platforms must therefore balance the benefits of transparency against the potential for such strategic manipulation when designing their information disclosure policies.