Institution: | 1. Department of Biostatistics, University of Nebraska Medical Center, Omaha, NE 68198, USA;2. Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1;3. Department of Biostatistics, University of Washington, Seattle, WA 98195, USA;4. Biostatistics Unit, HSR&D Center of Excellence, VA Puget Sound Health Care System Seattle, WA 98101, USA |