1. Center for Tobacco Research and Intervention, School of Medicine and Public Health; University of Wisconsin; Madison WI USA
2. Department of Medicine; University of Wisconsin; Madison WI USA
3. The Methodology Center; The Pennsylvania State University; University Park PA USA
4. William S. Middleton Memorial Veterans Hospital; Madison WI USA
5. Department of Biobehavioral Health and Human Development; The Pennsylvania State University; University Park PA USA