Assessing and Understanding Measurement Equivalence in Health Outcome Measures

From *Outcomes Research & Management, Merck & Co., Inc., West Point, Pennsylvania; and the †Center for Financing, Access, and Cost Trends, Agency for Healthcare Research and Quality, Rockville, Maryland. The views expressed in this article are those of the authors. No official endorsement by DHHS, the National Institutes of Health, the Agency for Healthcare Research and Quality, or Merck & Co., Inc. is intended or should be inferred. Reprints: Colleen A. McHorney, PhD, Merck & Co., Inc., Outcomes Research & Management, 770 Sumneytown Pike, WP39-166, West Point, PA 19486. E-mail: [email protected].