1. Thomas Covert is Assistant Professor of Microeconomics, Booth School of Business, University of Chicago, Chicago, Illinois.
2. Michael Greenstone is the Milton Friedman Professor in Economics and the College and Director of the Energy Policy Institute at Chicago, both at the University of Chicago, Chicago, Illinois. Greenstone is also Research Associates, National Bureau of Economic Research, Cambridge, Massachusetts.
3. Christopher R. Knittel is William Barton Rogers Professor of Energy Economics, Sloan School of Management, and Director of the Center for Energy and Environmental Policy Research, all at the Massachusetts Institute of Technology, Cambridge, Massachusetts. Knittel is also Research Associates, National Bureau of Economic Research, Cambridge, Massachusetts.