1. Annenberg Public Policy Center, University of Pennsylvania , Philadelphia, PA 19104 , USA
2. Department of Political Science, University of Michigan , 505 South State Street, Ann Arbor, MI 48106 , USA
3. Pew Research Center , 1615 L Street NW #800, Washington, DC 20036 , USA
4. Goldman School of Public Policy, University of California , 2607 Hearst Ave, Berkeley, CA 94720 , USA
5. Methodology and Quantitative Social Science Department, NORC at the University of Chicago , Chicago, IL 60637 , USA
6. Department of Political Science, Vanderbilt University , 230 Appleton Place, Nashville, TN 37203 , USA
7. Division for Statistical and Data Sciences, RTI International , Washington, DC 20005-3967 , USA
8. Center for Panel Survey Sciences, NORC at the University of Chicago , 55 East Monroe Street, Chicago, IL 60618 , USA
9. Alfred P. Sloan Foundation , 630 Fifth Avenue, New York, NY 10111 , USA
10. Department of Political Science, Duke University , 140 Science Dr, Durham, NC 27707 , USA
11. Langer Research Associates , Carmel, NY 10512 , USA
12. Department of Political Science, University of Pennsylvania , 133 South 36th Street, Philadelphia, PA 19104 , USA
13. Ipsos , Canton, GA 30115 , USA
14. Department of Government, University of Texas at Austin , 158 W 21st Street, Austin, TX 78712 , USA
15. Department of Political Science, Columbia University , New York City, NY 10012 , USA
16. Department of Political Science, Stanford University , Stanford, CA 94305 , USA
17. Department of Political Science, University of California Los Angeles , Los Angeles, CA 90095 , USA
18. Goldman School of Public Policy, University of California, Berkeley , Berkeley, CA 94720 , USA
19. National Academy of Sciences , 500 5th Street NW, Washington, DC 20001 , USA