A Second-best Argument for Low Optimal Tariffs, NBER Working Paper no. 28380, January 2021, joint with Lorenzo Caliendo, John Romalis and Alan M. Taylor, forthcoming 2023, Journal of International Economics
Estimating the Benefits of New Products, joint with Erwin Diewert, NBER working paper no. 25991, June 2019, forthcoming in K. Abraham, R. Jarmin, B. Moyer, and M. Shapiro, eds., Big Data for 21st Century Economic Statistics, Univ. of Chicago Press.
In Search of the Armington Elasticity, joint with Philip Luck, Maurice Obstfeld and Katheryn N. Russ. NBER Working Paper No. 20063, April 2014. Published version in the Review of Economics and Statistics, March 2018.
US Exports and Employment, Journal of International Economic, 120, September 2019, 46-58, joint with Hong Ma and Yuan Xu, NBER Working Paper No. 24056, November 2017. With replication package.
Optimal Choice of Product Scope for Multiproduct Firms, with Hong Ma, NBER working paper no. 13703, December 2007. Forthcoming in E. Helpman, D. Marin and T. Verdier, eds., The Organization of Firms in a Global Economy, Harvard University Press.
Technology in the Great Divergence, November 2001, with Gregory Clark. NBER working paper no. 8596. Published version in the Michael D. Bordo, Alan M. Taylor, and Jeffrey G. Williamson, eds, Globalization in Historical Perspective, Univ. of Chicago and NBER, January 2003, 277-314.