A decision support system (DSS) is a computer-based system, almost always interactive, designed to assist a manager (or another decision maker) in making decisions. A DSS incorporates both data and models to help a decision maker solve a problem, especially a problem that is not well structured. The data are often extracted from a transaction processing system or a data warehouse, but that is not always the case. The model might be simple, such as a profit-and-loss model to calculate profit given certain assumptions, or complex, such as an optimization model to suggest loadings for each machine in a job shop. DSSs and many of the systems discussed in the following sections are not always justified by a traditional cost-benefit approach; for these systems, many of the benefits are intangible, such as faster decision making and better understanding of the data.

An example of a DSS driven by transactions data is a police-beat allocation system used by a California city. This system enables a police officer to display a map outline and call up data by geographic zone, which shows police calls for service, types of service, and service times. The system’s interactive graphics capability lets the officer manipulate the maps, zones, and data to consider a variety of police-beat alternatives quickly and easily and takes maximum advantage of the officer’s judgment.