The authors are very grateful to Mark Roberts and Paul Grieco for their constant support and constructive comments. The authors also thank Scott Atkinson, Ying Fan, Gautam Gowrisankaran, Martin Hackmann, Hiroyuki Kasahara, Kenneth Judd, Robin Lee, Huihui Li, Charles Murry, Peter Newberry, Kathleen Nosal, Joris Pinkse, Thomas Quan, Marc Rysman, Philipp Schmidt-Dengler, John Turner, Daniel Xu, and participants in the Pennsylvania State University Industrial Organization workshop, the 13th Annual International Industrial Organization Conference, the 2015 Center for Economic and Policy Research–Journal of Industrial Economics School and Conference, and the 2016 Industrial Organization summer school of Shanghai University of Finance and Economics for their thoughtful comments. All errors are author's own responsibility.