| Institution: | 1. University of Toronto, Canada;2. I would like to thank Tom Holmes and Michael Keane for their encouragements and detailed comments. I would also like to thank Gautam Gowrisankaran, Hiroyuki Kasahara, Antonio Merlo, Stephen Schondelmeyer, and two anonymous referees for their valuable suggestions, and the participants at the UCLA Industrial Organization Workshop, Competition Bureau Canada seminar, and the Conference on Dynamic Models of Industry Evolution in Toronto for their useful feedback. I am grateful to Stephen Schondelmeyer for providing the IMS data and to Fiona Scott Morton for providing her data on patent expiration dates. I am responsible for all errors, omissions, and interpretations. Please address correspondence to: Andrew Ching, Rotman School of Management, University of Toronto, 105 St George Street, Toronto, ON, Canada M5S 3E6. Phone: 416‐946‐0728. Fax: 416‐978‐5433. E‐mail: . |
