1. a Center for Quality and Productivity Improvement
2. b Department of Industrial and Systems Engineering , University of Wisconsin-Madison , 610 Walnut Street, 575 WARF, Madison, WI, 53726, USA
3. c Department of Anesthesiology , University of Wisconsin School of Medicine , Bx 3272 Clinical Science Center-F6, Madison, WI, 53792, USA
4. d Pennsylvania State University, The Harold and Inge Marcus Department of Industrial and Manufacturing Engineering , 209 Leonhard Building, University Park, PA, 16802, USA