1. Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Division of Field Studies and Engineering, Health Informatics Branch, 1090 Tusculum Avenue, R‐17 Cincinnati OH 45226
2. Centers for Disease Control and Prevention, National Center for Health Statistics, Division of Research and Methodology, Collaborating Center for Questionnaire Design and Evaluation Research, 3311 Toledo Road Hyattsville MD 20782