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Book Contents
Glossary Contents

Decision Support Systems Glossary

by D. J. Power

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A B C D E

F G H I J

K L M N O

P Q R S T

U V W X YZ

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S

Scalability
The ability to scale hardware and software to support larger or smaller volumes of data and more or less users. The ability to increase or decrease size or capability in cost-effective increments with minimal impact on the unit cost of business and the procurement of additional services.

Semistructured Decisions
Decisions in which some aspect of the problem are structured and others are unstructured.

Sensitivity Analysis
Conducting a sensitivity analysis involves running a decision model several times with different inputs so a modeler can analyze the alternative results. See "What If" analysis.

Shell
An expert system development tool consisting of two stand-alone pieces of software: a rule set manager and an inference engine capable of reasoning with rules set built with the rule set manager. A shell is a complete expert system stripped of its specific knowledge.

Simulation
Simulation is a modeling technique for conducting one or more experiments that tests various outcomes resulting from a specific quantitative model of a system.

Spatial DSS
One sub-category of Data-Driven DSS is Spatial DSS. A Spatial DSS uses Geographic Information Systems technologies to support managers in analyzing data with a geographic or spatial component.

Specific DSS
A computer-based system that actually helps a person accomplish a specific task. "Specific DSS are the hardware/software that allow a specific decision maker or group of them to deal with specific sets of related problems" (cf., Sprague and Carlson, 1982, p. 10).

Spreadsheet
In the accounting world a spreadsheet was and is a large sheet of paper that lays everything out for a businessperson. It spreads or shows all of the costs, income, taxes, etc. on a single sheet of paper for a manager to look at when making a decision. An electronic spreadsheet organizes information into columns and rows. The data can then be "added up" by a formula to give a total or sum. The spreadsheet summarizes information from many sources in one place and presents the information in a format to help a decision maker see the financial "big picture" for the company. A program that has a collection of cells whose values can be displayed on a computer screen. By changing cell definitions and having all cell values reevaluated, a user can readily observe the effects of those changes. Decision support systems built using spreadsheet software are sometimes called Spreadsheet DSS. See "A Brief History of Spreadsheets" by Daniel Power at URL http://dssresources.com/history/sshistory.html.

Star Schema
A relational database schema organized around a central fact table joined to a few smaller dimension tables using foreign key references. The fact table contains raw numeric items that represent relevant business facts like price, discount values, number of units sold, dollar value, etc. The facts are typically additive and are accessed via dimensions. Since the fact tables are presummarized and aggregated along business dimensions, these tables tend to be very large. The basic premise of star schemas is that information can be classified into two groups: facts and dimensions. Facts are the core data element being analyzed. For example, units of individual items sold are facts, while dimensions are attributes about the facts. Dimensions are the product types purchased and the date of purchase. The star schema has also been called a star-join schema, data cube, data list, grid file, and multidimensional schema. The name star schema comes from the pattern formed by the entities and relationships when they are represented as an entity-relationship diagram (ERD). The results of a business activity are at the center of the star surrounded by the people, places, and things that come together to perform this activity. These dimensions are the points of the star.

Strategic Planning
A decision-making process in which decisions are made about establishing organizational purposes/mission, determining objectives, selecting strategies and setting policies.

Structured Decisions
Standard or repetitive decisions situations for which solution techniques are already available (also sometimed called routine or programmed decisions). The structural elements in the situation, e.g. alternatives, criteria, environmental conditions, are known, defined and understood.

Suggestion DSS
A Suggestion DSS uses Artificial Intelligence technologies like rules and frames to draw inferences and make suggestions and recommendations to managers and other decision-makers. See Knowledge-Driven DSS.

Symbolic Processing
Use of symbols, rather than numbers, combined with rules-of-thumb (or heuristics), in order to process information and solve problems.

Systems Development Life Cycle (SDLC)
SDLC is a process by which systems analysts, software engineers, programmers, and end-users build systems. It is a project management tool, used to plan, execute, and control systems develpment projects. The steps in the cycle include: 1) Determine user requirements; 2) Systems analysis; 3) Overall system design; 4) Detailed system design; 5) Programming; 6) Testing; and 7) Implementation. Each step is concluded by developing a written document that must be reviewed and approved before the next step begins.

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