Demographic and stratification research on migration, ageing, family change and social mobility, with a strong methodological component.

What we study. Researchers in the Population Studies cluster examine the demographic and social factors behind variation in health, mortality, ageing, education, family dynamics, urban living and migration. Work in the cluster estimates international and internal migration flows and their human capital composition; analyses social mobility and the intergenerational transmission of advantage; examines how educational expansion changes the value of credentials and skills; and studies how migration reshapes families across borders and across the rural–urban divide within China. The cluster also develops methods: causal inference for stratification research, computational and machine-learning approaches to demographic estimation, digital trace data for monitoring migration, and cross-national comparison.

Recent work. Guy Abel’s methods for estimating international migration flows for 230 countries was recently published in Nature (2026) and he has consulted on migration measurement for the IOM, the ILO and the World Bank; his current GRF projects cover the human capital of migration flows and bilateral migrant population sizes in the Asia Pacific. Satoshi Araki’s work on educational expansion and the economic value of credentials appeared in the American Sociological Review (2020), with cross-national analysis of the “skills trap” in the European Sociological Review (2025). Lai Wei and Yu Xie set out a causal-intervention approach to social mobility in Sociological Methods & Research (2025). Duoduo Xu’s research on hukou, school segregation and educational inequality in urban China was published in 2022. Eric Fong directs the Hong Kong General Social Survey, funded by the Kwok Yat Wai Charitable Fund.