1. College of Information Studies and in the Joint Program in Survey Methodology, University of Maryland, 1218 LeFrak Hall, College Park, MD, USA
2. Survey Research Center, Institute for Social Research, University of Michigan, 426 Thompson Street, Ann Arbor, MI, and in the Joint Program in Survey Methodology, University of Maryland
3. Survey Research Center, Institute for Social Research, University of Michigan, and in the Joint Program in Survey Methodology, University of Maryland