professor emeritus of sociology, University of Illinois at Urbana-Champaign
Stephen K. Doig
Knight chair in journalism, Cronkite School of Journalism
Arizona State University
How many people attended Jon Stewart's rally last weekend, or Glenn Beck's rally last summer? It depends on who you ask. Two crowd-counting experts explain the "gold standard" for measuring crowd size, and discuss why some rally organizers might disagree with the counts.