The Economic Survey 2016-17 devotes a small chapter to the question of measuring migration. The authors discuss two new methods:
- Cohort-based Migration Metric (CMM)
- Using Railways Data
CMM "considers net migration to be the percentage change in population between the 10-19 year-old cohort in an initial census period and the 20-29 year old cohort in the same area a decade later, after correcting for mortality effects." This method throws up very interesting results. Tamil Nadu and Kerala show huge increases in inward migration while data from Maharashtra and Delhi shows that inward migration is slowing down.
The idea behind Railways Data is "to use net annual flows of unreserved passenger travel as a proxy for work-related migrant flow." Unreserved is interesting because there is no limit set by the railways and the bookings are free to expand and contract based on demand. This throws up the very interesting migration route from Gujarat to Tamil Nadu.
The entire document is full of fascinating insights and is written in very readable prose. It can be downloaded here.