CHAPTER 2 LITERATURE REVIEW 2.1. Decision Support System In 1971, Michael S. Scott Morton expressed the first concept of Decisio Support Systems (DSS) under the term Management Decision Systems in his book titled "Management Decision Systems: Computer-Based Support for Decision Making". Scott Morton focused on how computers and analytical models could help or support managers in making key decisions. Decision Support Systems (DSS) is one of many technologies of Management Support System. DSS is the simplest technology compared to other Managemen Support System technologies. However, DSS is sometimes used as an umbrella term to describe any other computer-based system used to support decision-making in an organization (Aronson and Turban, 1998). The other technologies of Management Support System are: • Group Suppmt Systems (GSS) or Group Decision Support Systems (GDSS) • Executive information Systems (EIS) or Executive Support Systems (ESS) • Expe1t Systems (ES) 1 • Artificial Neural Networks (ANN) • Hybrid Support Systems 2.2. Definition of DSS There are many definitions for DSS because the concept of DSS is extremel broad and its definitions vary, depending on the author's point of view. Aronson and Turban (1998) said, "There is no universally accepted definition of DSS". Some of the definitions gathered from past literatures are listed below t illustrate how vary the definitions ofDSS are. • "DSS are interactive computer-based systems, which help decision makers utiliz data and models to solve unstructured problems" (Garry and Scott Morton, 1971) • Keen and Scott Morton (1978) provide another definition as "Decision suppor systems couple the intellectual resources of individuals with the capabilities of th computer to improve the quality of decisions. It is a computer-based suppor system for management decision makers who deal with semi structure problems". • Carlson and Sprague (1982) define DSS as "interactive computer based system that help decision makers use data and models to solve ill-structured, unstructure or semi-structured problems" ll • Bonczek, Holsapple and Whinston (1980) define a DSS as a computer-based system consisting of three interacting components: a language system, a knowledge system, and a problem-processing system. • Little ( 1970) defines DSS as a "model-based set of procedures for processing data and judgements to assist a manager in his decision-making". • Chang and Moore (1980) define DSS as extendible systems capable of supporting ad hoc data analysis and decision modelling, oriented toward future planning, and used at irregular, unplanned interval. • "DSS are interactive, computer-based systems that aid users in judgement and choice activities". (Druzdzel and Flynn, 2000) • Keen (1980) defines DSS as the product of a developmental process in which the DSS user, the DSS builder, and the DSS itself are all capable of influencing one another, resulting in system evolution and pattern of use. The varieties of definitions are happen because each person uses a differen point of view as the basis of the definitions. Gorry and Scott Morton use problem type and system function, Little uses system function and interface characteristics Alter uses usage pattern and system objective, Chang and Moore use usage pattern and system capabilities, Bonczek et a!. use system components, and Keen uses development process. 1 After reviewing a lot of definitions, the researcher came to a conclusion tha Decision Support Systems is a computer-based system to support and improv decision-making for unstruct11red and semi structured problem. 2.3. Characteristic and Capability of DSS As there agreement on is no agreement over what a DSS standard characteristics and is, there is also no definit capabilities of DSS. Some of th characteristics and capabilities that made an ideal set, based on Aronson and Turba (1998), and Sprague (1980) are listed below. • A DSS should provide support for decision-making, with emphasis on semi structured and unstructured problems by bringing together human judgment an computerized information. • A DSS should provide support for various managerial levels, ranging from to executives to line managers and assisting integration between the levels wheneve appropriate. • A DSS should provide support to individuals as well as to groups. Less structure problems often require the involvement of several individuals from differen departments and organizational levels. • A DSS should provide support to several interdependent and/or sequentia decisions. • A DSS should provide support for all phases of the decision-making process intelligence, design, choice, and implementation. • A DSS should provide support a variety of decision-making processes and styles but not be dependent on any one. • A DSS should be adaptive over time. The decision maker should be able t confront new conditions quickly, and at the same time adapt the DSS to meet th new conditions. • A DSS should be flexible. Thus, users can add, delete, combine, change, o rearrange basic elements of DSS. • A DSS should be easy to use. Users must feel at home with DSS. • A DSS should have an English-like interactive human-machine interface, whic can greatly increase the effectiveness ofDSS. • A DSS specifically aims to support and not to replace the decision maker. Th decision maker has complete control over all steps of the decision-making proces in solving a problem. • A DSS should be able to use mathematics and statistics models for analysin decision-making situations. The modelling capability enables experimenting wit different strategies under different configurations. • A DSS should provide access to a variety of data source, formats, and types. 1 2.4. Major Component of DSS According to Sage (1991 ), there are three fundamental components of DSS They are Database Management System (DBMS), Model Base Management System (MBMS), and Dialog Generation and Management System (DGMS). While a variety of DSS structure exists, the three above components can be found in many DSS architectures and play a prominent role in their structure. DSS MODEL BASE DBMS MBMS DSS DATA BASE DGMS DSS USER Figure 2.1. Architecture of a DSS Figure 2.1 shows us the architecture of a DSS and the relationships between components. Essentially, the user interacts with the DSS through the DGMS. Then, it 1 communicates with the DBMS and MBMS, which screen the user and the use interface from the physical details of the model base and database implementation. Database Management System A database management system (DBMS) separates the user from the physica aspects of the database structure and processing. It also provides logical dat structures (as opposed to the physical data structures) and informs the types of dat that are available and how to gain access to them. A DBMS functions are creation-generation database and restructure database updating (adds, deletes, edits, changes) database, retrieving data for queries an report generation, and performing complex data manipulation task. Model Base Management System The role of model base management system (MBMS) is similar to that of DBMS. It provides independence between specific models that are used in a DS from the applications that use them. The functions of MBMS are creating model (either from scratch or from existing models or from building blocks), maintainin (updates, stores, retrieves, changes) model base, generating reports, manipulatin models based on queries, and interrelating models with a database. 1 Dialog Generation and Management System The dialog generation and management system (DGMS) is also called (i broader tenn) user interface. As the users of DSS are often managers who are no computer-trained, DSS need to be equipped with intuitive and easy to use interface DGMS is the most important component of DSS because its primary responsibility i to enhance the ability of the user to utilize and benefit from the DSS. The power flexibility, and ease of use characteristics of DSS are derived from this componen (Sprague and Watson, 1996). Others state that the user sees the user interface as the system because the use sees only this part of DSS (Bentley and Whitten, 1997). An inconvenient use interface is one of the major reason why executives have not use DSS (Aronson an Turban, 1998). The functions of DGMS are handling variety of dialog styles, presenting dat in a variety of formats and media, providing help capabilities to user, and linking t DBMS and MBMS. 2.5. Classification of DSS There are many classifications of DSS. According to Holsapple and Whinsto (1996), DSS can be classified into six frameworks. They are Text-oriented DSS Database-oriented DSS, Spreadsheet-oriented DSS, Solver-oriented DSS, Rule oriented DSS, and Compound DSS. 1 Text-oriented DSS Text-oriented DSS is needed because a lot of information is often stored in a textual fom1at and need to be accessed by the decision makers. Nowadays, the amount of information to be searched by the decision maker is growing exponentially. Therefore, it is necessary to retrieve and process text documents or its fragments effectively and efficiently. A text-oriented DSS supports a decision maker by electronically keeping track of textually represented information that could have a bearing on decisions. It also allows documents to be electronically created, revised, and viewed as needed. Database-oriented DSS In database-oriented DSS, the database plays a major role in the DSS sttucture. In this type of DSS, data are organized in a highly structured forma (relational or object-oriented) rather than being treated as streams of text. Database oriented DSS has strong report generation and query capability features. In the early generation of database-oriented DSS, relational database configuration is largely used. The information handled by relational databases tends to be voluminous, descriptive, and rigidly stmctured.