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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)
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•
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.
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