We have benefited from the detailed comments of a number of individual
s including Mark Bils, Robert Chirinko, Michael Keane, John Kennan, Ma
rilyn Manser, Robert Moffitt, Ed Prescott, Gary Solon, Scott Sumner, a
nd two anonymous referees. Nathalie Simon, Lucia Foster, and Catherine
Buffington provided excellent research assistance. The views expresse
d are those of the authors alone, and do not necessarily reflect the o
fficial position of the U.S. Bureau of Labor Statistics.