A forecast is necessary to every decision or policy position. Essentially, the policy or decision one advocates assumes a forecasts of what will happen as a result of the action being recommended. Consequently forecasting as an activity permeates all aspects of public management and public policy making.
Forecasts can be generates in many different ways using many different approaches.
Some forecasts are purely based on intuition and human judgement, others require complex mathematical and computer based models. Some forecasts rely heavily on social and physical science theory while others do not. Though approaches and techniques of forecasting come from many different disciplines including economics, mathematics, engineering, psychology and statistics, it has only been over the last 15 years that forecasting has become an identifiable and serious area for study. Most forecasting research up through 1979 was primarily aimed as developing 'new' techniques and demonstrating, often on the basis of one or two examples, their superiority to existing forecasting tools. This new orientation has attempted to identify which contingencies or situations favor use of which forecasting method.