1. Gregory S. Warrington is an associate professor in the Department of Mathematics and Statistics at the University of Vermont in Burlington, Vermont. This work was partially supported by a grant from the Simons Foundation (#429570). Dr. Warrington is especially indebted to Gary C. Jacobson for sharing his data on U.S. congressional elections. He thanks Jeff Buzas for helpful conversations, and the anonymous reviewers whose careful work greatly improved this article.