NBER WORKING PAPER SERIES WHAT ARE WE WEIGHTING FOR? Gary Solon Steven J. Haider Jeffrey Wooldridge Working Paper 18859 http://www.nber.org/papers/w18859 NATIONAL BUREAU OF ECONOMIC RESEARCH 1050 Massachusetts Avenue Cambridge, MA 02138 February 2013 We are grateful for helpful comments from David Autor, Raj Chetty, John DiNardo, Todd Elder, Mike Elsby, Osborne Jackson, Fabian Lange, Jason Lindo, Jim Ziliak, and seminar participants at the University of Kentucky. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer- reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications. © 2013 by Gary Solon, Steven J. Haider, and Jeffrey Wooldridge. All rights reserved. Short sections of text, not to exceed two paragraphs, may be quoted without explicit permission provided that full credit, including © notice, is given to the source.