Audit correspondence studies are field experiments that test for discriminatory behavior in active markets. Researchers measure discrimination by comparing how responsive individuals (“audited units”) are to correspondences from different types of people. This article elaborates on the tradeoffs researchers face between sending audited units only one correspondence and sending them multiple correspondences, especially when including less common identity signals in the correspondences. We argue that when researchers use audit correspondence studies to measure discrimination against individuals that infrequently interact with audited units, they raise the risk that these audited units become aware they are being studied or otherwise act differently. We also argue that sending multiple pieces of correspondence can increase detection risk. We present the result of an audit correspondence study that demonstrates how detection can occur for these reasons, leading to significantly attenuated (biased toward zero) estimates of discrimination.

审计对应研究是测试活跃市场中歧视行为的现场实验。研究人员通过比较个体（“被审计单位”）对来自不同类型人的信件的反应程度来衡量歧视。本文详细阐述了研究人员在仅向被审计单位发送一封信件和向他们发送多封信件之间所面临的权衡，尤其是在信件中包含不太常见的身份信号时。我们认为，当研究人员使用审计对应研究来衡量对不经常与被审计单位互动的个人的歧视时，他们会增加这些被审计单位意识到他们正在被研究或以其他方式采取不同行为的风险。我们还认为发送多封信件会增加检测风险。