Participants in the general discussion pointed out that once cities reach a certain size in terms of population, city size may adversely affect people's employment. Iikka Korhonen therefore suggested including city scale nonlinearly in the estimation. Jie Li agreed with this comment and noted that high-skilled workers seem to be particularly responsive to external factors such as pollution and more likely to migrate. Don Hanna added that not only population size matters but also the physical space of a city, and hence that should be accounted for in the estimation.
Quoc Huy Vu and Prema-chandra Athukorala inquired whether migrant workers, many of whom are self employed and working in the non-tradable sector, are included in the data sets. Ming Lu explained that migrant workers are not included in the estimation because most city-based migrants are employed because of China's hukou or household registration system. The exclusion of migrant workers is...