3 VALUE ESTIMATES OF INPUT VARIABLES AND HEALTH MANPOWER PROJECTIONS

The introduction of variability and stochastic processes in health man power projections may help health planners cope with the inherent prob lem of uncertainty in the future. However, limited data and the comple x nature of health manpower make it very difficult or even impossible to estimate the probability distribution of input variables. In this p aper, two statistical methods are discussed and compared for approxima ting a probability distribution based on imperfect data. The common fe ature of the two methods is that they use minimum, maximum, and most l ikely values, which can be estimated by people with little knowledge o f statistics and probability. In addition, the methods can be used to analyse variables with a symmetrical as well as non-symmetrical probab ility distribution. An example is provided of the application of the m ethods to health manpower projections in China.