and Senior Fellow to The Conference Board

This is a revised draft of working paper #08-02 of the Economics Program of the Conference Board. We would like to thank Martin Fleming and Baruch Lev for their comments on earlier drafts, as well as Gail Fosler, Bart Van Ark, Carol Corrado, and other colleagues at the Conference Board. Kathleen Miller and Mary Sinclair provided valuable assistance in preparing this paper. Opinions and interpretations, and any remaining errors, are the responsibility of the authors.