To avoid data entry errors in online systems, a preformatted screen approach may be used. It is a screen prompting approach that involves the display on a monitor of a set of boxes for entry of specified data items. The format may even be in the form of a copy of a transaction document. This technique is best suited to conversion of data from a source document.

Validation is a step in the simulation procedure. Some assurance is needed that the results of the experiment will be realistic. This assurance requires validation of the model --often using historical data. If the model gives results equivalent to what actually happened, the model is historically valid. There is still some risk, however, that changes could make the model invalid for the future.

Materials requirements planning (MRP) is a system that translates a production schedule into requirements for each component needed to meet the schedule. It is usually implemented in the form of a computer-based information system designed to plan and control raw materials used in production. It assumes that forecast demand is reasonably accurate and that suppliers can deliver based upon this accurate schedule. MRP is a centralized push-through system; output based on forecasted demand is pushed through to the next department or to inventory.

Over some intermediate range of prices, the reaction to a price increase for prestige goods is an increase, not a decrease, in the quantity demanded. Within this range, the demand curve is upward sloping. The reason is that consumers interpret the higher price to indicate a better or more desirable product. Above some price level, the relation between price and quantity} demanded will again became negatively sloped.