1. Nicholas Bloom is William D. Eberle Professor of Economics, Stanford University, Stanford, California. Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts.
2. John Van Reenen is Gordon Y. Billard Professor in Management and Economics, Massachusetts Institute of Technology, Cambridge, Massachusetts. Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts.
3. Heidi Williams is Professor of Economics, Stanford University, Stanford, California. Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts.