title: Risk adjustment for comparing hospital quality with surgery: how many variables are needed?
authors.affiliation: Michigan Surgical Collaborative for Outcomes Research and Evaluation, Department of Surgery, University of Michigan, Ann Arbor, MI 48104, USA. jdimick@umich.edu
authors.forename: Justin B
authors.initials: JB
authors.lastname: Dimick
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Osborne
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Hall
authors.forename: Clifford Y
authors.initials: CY
authors.lastname: Ko
authors.forename: John D
authors.initials: JD
authors.lastname: Birkmeyer