In recent years, many individuals have developed models to predict the future course of the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) epidemic at the local, state, and national levels. The number of forecasters and resulting projections reflects not only the complexity and uncertainties in predicting the epidemic, but also the critical importance of such estimates.1 Many health care policies are based on these forecasts, which influence the scope and direction of both public and private initiatives related to HIV.
Overall, the number of reported cases of AIDS in the United States continues to increase. During 1989, 35 238 cases were reported, for a yearly increase of 9.4% over the 32 196 cases reported during 1988. This increase is lower than in past years, partly because of the large number of previously diagnosed cases reported in 1988 that met only the expanded AIDS case definition.2 However, even after