Brookings Papers on Economic Activity (BPEA) provides academic and business economists, government officials, and members of the financial and business communities with timely research on current economic issues. Contents: On Secular Stagnation in the Industrialized World, Lukasz Rachel and Lawrence H. Summers A Forensic Examination of China's National Accounts, Wei Chen, Xilu Chen, Chang-Tai Hsieh, and Zheng Song A Unified Approach to Measuring u*, Richard K. Crump, Stefano Eusepi, Maric Giannoni, and Ays ̧egül S ̧ahin Fiscal Space and the Aftermath of Financial Crises: How It Matters and Why, Christina D. Romer and David H. Romer Okun Revisited: Who Benefits Most from a Strong Economy? Stephanies R. Aaronson, Mary C. Daly, William L. Wascher, and David W. Wilcox On the Economics of a Carbon Tax for the United States, Gilbert E. Metcalf