ABSTRACT
Understanding the past course of the HIV/AIDS pandemic in sub-Saharan Africa and how it is likely to evolve from here would be a difficult task even with good data, but the data that we must use as the foundation of any analysis are sparse and often of poor quality. Nevertheless, it is important to try to learn from the past and to forecast the future, because some decisions that need to be made today depend on what we expect the future to be. For example, in water-scarce regions, decisions on whether or not to start building expensive water infrastructure depend, in part, on the likely future population size. Similarly, if we wanted to try to understand the effects of the epidemic on economic growth, we would need to assess, among other things, the likely number of deaths of more-educated and less-educated workers.
