Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition

Information Systems

This issue of “processing” data in a map form (analog) versus symbol form (digital) brings us to the matter of processing or handling data in general. The conceptual model we will use is that data are processed to produce information. Actually, the terms are not absolute, because what is information to a person filling one role may be data to someone else filling another. However, the idea of a before–after concept, distinguishing the two states as data and information, turns out to be useful, so we employ it.4

An information system, in the context of this material, is a set of steps, or set of processes that is executed by a “device” to produce information. We choose to call the symbols that are input to the process by two names: data and parameters. “Data” we have discussed along with its formation into bases. “Parameters” we consider to be information, which the user of an information system supplies at the time of use of the system. Such parameters might specify which data in the base are to be used, how they are to be combined, what the format of the resulting information—output—is to be, and other specifications and/or constraints.

For an example, a professor may assign a student the task of compiling a bibliography of the works of Shakespeare. The database might be a library catalog; the parameters are such descriptive terms as “bibliography.” “Shakespeare,” “word-processed”; the device is the student, who, with his eyes, pencil, word processor, and ...