A methodology for projecting sub-national populations allowing for the impact of HIV/AIDS and where data are limited and defective

Rob Dorrington, University of Cape Town
Tom A. Moultrie, University of Cape Town

Sub-national population projections are fraught with complexity at the best of times. It is axiomatic that as the population being modelled represents a smaller proportion of the national whole, the least understood of the three major demographic forces – migration (local and international) – plays an increasingly significant role, while sub-population specific estimates of the other demographic variables may not be available or reliable. This paper describes an approach to projecting sub-national population dynamics in 28 districts of a country (Botswana) whose aggregate population is less than one-fifth that of New York City. In doing so, the sum of the regional projections must remain consistent with that of the national population, while taking into account the careful incorporation of HIV epidemiological dynamics in each region and with the added difficulty of working with severely limited and defective census and survey data. In the process, interesting insights into the regional demographic dynamics of the country are developed.