Forecasting System Inputs:

The information/data required as input for the preparation of a forecast of demand can be obtained from internal and/or external sources.

For a short- and medium-term forecast in a relatively stable environment, one usually relies on internal sources, often supported by some kind of economic forecast. Historical data in the form of a time series on previous order-volumes or sales, expert opinions of company staff, and results of special surveys are frequently found useful as information inputs produced internally.

For formulating long term strategies on new products, processes, and markets, information from external sources concerning competitors, new trends in technology and likely developments on the social, political, economic and international scenario become extremely valuable. Additional sources of information can include trade journals, private consulting firms, industry experts, and government agencies.