Kathleen Beegle of the World Bank is presenting her paper, “Internal Migration and Poverty Reduction in Tanzania: Evidence from a Long-Term Tracking Survey” at the Massachusetts Avenue Development Seminar (MADS) on Tuesday, November 6.

In 2004 Kathleen and her co-authors re-traced thousands of respondents to household surveys conducted in Tanzania in 1991-1994. What a task! She and her co-authors find that, over a decade, internal migrants see income gains four times that of their non-migrant peers. This gain not necessarily a reflection of the effects of migration per se (after all, it may the high potential earners that self-select into migration). Her main point, I think, is that panel surveys that do not track migrants (i.e. virtually ALL panel surveys) may seriously overestimate poverty and underestimate economic growth.

Tracking migrants comes at a monstrous cost. In our surveys of youth in a conflict zone, close to 2 in 5 youth had left their village of origin when we followed them up ten years later. Tracking them probably took up 70 percent of our time and budget. I’m still waiting to do an analysis of our migrants found and unfound (we collected data on the unfound youth from family members). For those interested, however, Duncan Thomas and co-authors have an excellent paper on the utility and cost of tracking studies — Lost but Not Forgotten.