ills, Inc., 773 F.2d 561 (4th Cir. 1985); United States v. County of Fairfax, 629 F.2d 932, 940 (4th Cir. 1980); see generally Ramona L. Paetzold & Steven L. Willborn, The Statistics of Discrimination: Using Statistical Evidence in Discrimination Cases § 4.03 (2014) (describing the use of proxy data when actual d