1. Department of Economics, University of Waterloo, Ontario, Canada
2. Big Data Research Lab, University of Waterloo, Ontario, Canada
3. Senior Research Fellowship of Labor and Worklife Program, Harvard University, Cambridge, MA, USA
4. Department of Economics, The Chinese University of Hong Kong, Hong Kong, People's Republic of China
5. School of Mathematical and Computational Sciences, University of Prince Edward Island, Prince Edward Island, Canada
6. School of Economics, Xiamen University, Xiamen, People's Republic of China