Measuring the effect of peers on individuals' outcomes is a challenging problem, in part because individuals often select peers who are similar in both observable and unobservable ways. Group formation experiments avoid this problem by randomly assigning individuals to groups and observing their responses; for example, do first-year students have better grades when they are randomly assigned roommates who have stronger academic backgrounds? In this paper, we propose randomization-based permutation tests for group formation experiments, extending classical Fisher Randomization Tests to this setting. The proposed tests are justified by the randomization itself, require relatively few assumptions, and are exact in finite-samples. This approach can also complement existing strategies, such as linear-in-means models, by using a regression coefficient as the test statistic. We apply the proposed tests to two recent group formation experiments.

翻译：衡量同龄人对个人结果的影响是一个具有挑战性的问题,部分原因是个人往往选择在可观察和不可观察方式上都相似的同龄人。集体形成实验通过随机将个人分配到团体并观察其反应来避免这一问题;例如,当第一年的学生是随机分配到具有较强学术背景的室友时,他们的成绩会更好吗?在本文中,我们提议对集体形成实验进行随机化的变异测试,将经典渔业随机化测试推广到这一环境。提议的测试有随机化本身的正当理由,需要相对较少的假设,并且精确地体现在有限的样本中。这一方法还可以补充现有的战略,例如线性中值模型,用回归系数作为测试数据。我们对最近的两个集体形成实验应用了拟议的测试。</s>