NBER Working Paper No. 15341
---- Acknowledgments ----
Paper prepared for the Handbook of the Economics of Innovation, Bronwyn H. Hall and Nathan Rosenberg (eds.), Elsevier-North Holland, in process. I would like to thank the many people that commented on earlier drafts: Susanto Basu, Erwin Diewert, John Haltiwanger, Janet Hao, Michael Harper, Jonathan Haskell, Anders Isaksson, Dale Jorgenson, and Paul Schreyer. Remaining errors and interpretations are solely my responsibility. JEL No. O47, E01. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.