Shifts in graduate mobility between Chinese cities during COVID-19: evidence from mobile phone data
利用九城市超百万毕业生的手机信令数据，分析2019至2021年297个城市间毕业生流动的变化，发现地理距离、人口流动和服务业就业持续影响流动，疫情期间技术合作网络作用增强，传统经济指标减弱，封锁政策影响不显著。
This study analyses how graduate mobility between Chinese cities changed before, during and after the COVID-19 pandemic. Using mobile phone signalling data on more than one million graduates from nine cities, we estimate gravity models to explain graduate flows between 297 cities from 2019 to 2021. We find that geographical distance, prior population flows and service-sector employment consistently influenced mobility. During the pandemic, technological collaboration networks became more important, while traditional economic indicators weakened. Lockdown policies had no significant impact. These results emphasise the importance of networks in graduate mobility and suggest that service-oriented cities are more attractive in times of uncertainty.