e treatment and impact claims. "The probative value of other discriminatory acts depends . on the nature of the discrimination charged." Hunter v. Allis-Chalmers Corp., Engine Div., 797 F.2d 1417, 1424 (7th Cir. 1986), abrogated on other grounds by Patterson v. McLean Credit Union, 491 U.S. 164, 109 S. Ct. 2363, 1