Alan G. Isaac
Department of Economics 
American University
Washington, DC 20016-8029 USA
office: (202) 885-3785
email: aisaac@american.edu

Mary E. Hansen
Department of Economics
American University
Washington, DC 20016-8029 USA
office: (202) 885-3793
email: mhansen@american.edu

Martha A. Starr
Department of Economics
American University
Washington, DC 20016-8029 USA
office: (202) 885-3747
email: mstarr@american.edu