A forecast is a statement, usually in probabilistic terms, about the future state or properties of a system based on a known past and present. A CONDITIONAL FORECAST states in probabilistic terms what the future will be if a course of action is taken. A forecast that states with a high degree of confidence what the future will be is referred to as a
prediction. A forecast that is a hypothesis rather than a formally justified inference from past data is referred to as a
scenario. Forecasting techniques range from expert judgments to mathematical forecasting
models. The FORECASTING LEAD (forecasting horizon) is the length of time ahead of now for which one can make a reasonable forecast. It depends, in the general sense, on available data. A forecast that makes itself come true is referred to as a
self- fulfilling forecast. For example, a forecast for the rapid growth of a certain city may encourage business to locate there, thus causing the forecast to be realized. (IIASA)
