A method implemented by a computer comprising collecting historical data for a plurality of items; categorizing each of the plurality of items; assigning at least one of the plurality of items as an index item for at least another of the plurality of items; collecting data for a plurality of context parameters related to at least one of the plurality of items; and forecasting a value for one of the plurality of items needed over a future period of time, wherein the method reduces a data storage capacity requirement for the computer and increases said computer's processing speed.