To construct my data set of national security commissions, I began with Amy Zegart's data set of commissions that reported between 1981 and 2001. Zegart's data set consists of commissions that addressed all issue areas and includes information on each panel's source of authority, dates of operation, and membership size, as well as Zegart's assessment of each commission's purpose. Her data set is drawn from the Encyclopedia of Government Advisory Organizations, and includes most national security commissions from 1981 to 2001.

I pulled out the national security commissions in Zegart's data set and supplemented that group in several ways. First, I searched the Encyclopedia of Government Advisory Organizations for national security commissions that reported between 2002 and 2006. Second, I conducted systematic searches of other valuable sources of information on commissions: a government database of annual reports mandated by the Federal Advisory Committee Act (available at http://www.fido.gov/facadatabase), and coverage of commissions in the New York Times and Washington Post. I searched these newspapers by using LexisNexis and identifying all articles between January 1, 1981 and December 31, 2006 that contained the words “panel” or “commission,” and “security,” “defense,” or “military.”