In a government auction program where first‐price auctions generate significantly higher revenue than English auctions, I document evidence that bidders are uncertain about the number of auction entrants. Motivated by additional data evidence, I estimate a structural model of auctions in which rivals' participation is stochastic, allowing for bidders' risk aversion and asymmetry. Counterfactual simulations reveal that bidders' uncertainty about the number of entrants, combined with risk aversion, substantially softens the revenue impact of low competition in first‐price auctions. This explains the observed revenue patterns and uncovers an empirically important reason for sellers to favor first‐price auctions over English auctions.

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不了解竞争：证据和对拍卖设计的影响

在政府拍卖计划中，一价拍卖产生的收入比英国拍卖高得多，我记录了证据，表明竞标者不确定拍卖参与者的数量。受其他数据证据的激励，我估计了竞价的结构模型，其中竞争对手的参与是随机的，从而允许竞标者规避风险和不对称。反事实模拟显示，竞标者对参赛者数量的不确定性加上风险规避，大大减轻了低价竞标中的低收入对收入的影响。这解释了观察到的收入模式，并揭示了从经验上讲，卖方比英国拍卖行更偏爱首价拍卖的重要原因。