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 complex at the best of times. As the population being modelled represents a potentially small proportion of the national whole, the least understood of the three major demographic forces – migration (local and international) – plays an increasingly significant role, while, in addition, 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. Apart from having to ensure that the sum of the regional projections remains consistent with that of the national population, the projection needs to incorporate HIV epidemiological dynamics in each region and work with severely limited and defective census and survey data. In the process, interesting insights into the regional demographic dynamics of the country are developed.