1. University of Southern California, Los Angeles, CA, USA.
2. National Bureau of Economic Research, Cambridge, MA, USA.
3. Yale University, New Haven, CT, USA.
4. University of California, San Diego, CA, USA.
5. Massachusetts Institute of Technology, Cambridge, MA, USA.
6. Resources for the Future, Washington, DC, USA.
7. University of Maryland, College Park, MD, USA.
8. University of California, Davis, CA, USA.
9. University of California, Berkeley, CA, USA.
10. University of Pennsylvania, Philadelphia, PA, USA.
11. Carnegie Mellon University, Pittsburgh, PA, USA.