1. DSS & Warehousing Systems
Chapter 6
Efrem Mallach
Prepared by
Luvai Motiwalla
Irwin/McGraw-Hill
Copyright © 2000 by The McGraw-Hill Companies, Inc. All rights reserved.

2. DSS Software Tools Introduction Database Management systems
Information retrieval packages
Specialized modeling languages
Statistical data analysis packages
Forecasting packages
Graphing packages
Programming languages for DSS
DSS user interfaces
User interface styles
Hypertext/hypermedia

3. Introduction DSS software categories Standard packages
Specialized tools and generators
Pages 198 to 201
There are four fundamental ways to obtain any software capability: to purchase a turnkey package, to customize a package, to use specialized tools or generators designed for the task at hand, or to write necessary programs from scratch.
Since a decision support system is software, these approaches apply to DSS as well. The choice between packages (customized or not) and custom software usually depends on
The degree to which your needs resemble those of many other organizations.
The financial impact of the application.
Standard packages:- to help make specific decisions have been developed for a few common decisions.
Specialized tools and generators;- DSS tools and DSS generators are used by developers because. DSS tools would generally be used to create DSS generators, which in turn would generate the specific DSS used by decision makers.A DSS generator will usually have the capability to become or to create an entire DSS.
The major categories of specialized software use to assist DSS development are 1) database management packages, 2) Information retrieval packages, 3) specialized modeling packages and languages, 4) statistical data analysis packages, 5) forecasting packages, 6) graphing packages.

4. Database Management Systems
A data base management system allows you to store data in an organized form and retrieve it in on the basis of specified selection criteria.
The four basic database structures: hierarchical,network(or codasyl),relational and multidimensional.
Pages 204 to 211
A hierarchical database manager links records of different types in a strict hierarchy from top to bottom. Each record , except those at the top level, is associated with a specific parent record.It is weaker in handling more complex relationships, such as many to many relationships.
A network database structure more flexibility in the way different files are linked. The use of the term network here is to describe a database structure. Compare to hierarchical DBMS, network DBMS software is more complicated because it must be able to represent more complex data structures.Many network DBMS follow the CODASYL standard.
A relational DBMS stores its data in the form of two dimensional tables. The database management software links record from several tables by matching corresponding fields.Relational databases provide a good foundation for a data ware house designed to respond to unplanned queries.The advantage of relational DBMS is interface standardization.
A multi dimensional DBMS is particularly useful in data warehouses.

5. Information Retrieval Packages
Most informational retrieval packages are designed to pull user specific data out of a file or a database.
Systems that retrieve few irrelevant items are said to have high precision, and systems that miss few relevant items are said to have high recall.
Pages 212 to 213

6. Specialized Modeling Languages
What are the advantage sand disadvantages of using spreadsheets for business planning?
Pages 213 to 218
Many DSS incorporate models of various types. The packages do not incorporate any models themselves. They simply make it easier for the user to define the characteristics of his or her model to the computer.
Taking the example of a spreadsheet which is a standard tool, which most knowledge workers and managers manipulate accounting models.
A spreadsheet, I its basic form, looks like a two dimensional grid of cells.They can create several kinds of graphs automatically from the data they calculate.. They may extend two dimensional grid to three or more dimensions.
Disadvantages:-Errors in data introduced are not traceable or detected. This is because each sell is independent of each other, and formulas are normally hidden from the reader and and are scattered all over a spreadsheet.
The limitations of the basic spreadsheet paradigm,cells containing formulas that carry out calculations on data in other cells, are too confining for some applications.
To alleviate the problems specifically designed software is being used such as IFPS form Execucom. It resembles a spreadsheet on the surface. The difference is that the model exists as a separate, easily visible, and easily auditable entity. The major difference between financial modeling programs and spreadsheet programs is the way in which the model is set up. Auditing packages, help find both accidental and malicious errors in standard spreadsheet.

7. Statistical Data Analysis Packages
What do statistic packages do ?
Pages 218 to 224
By determining how a system has reacted to certain factors I the past, we hope to estimate how it will react in the future and thus gauge the likely outcome of our decisions. These decisions are often statistical.
Most statistical packages allow a decision maker to deal with more than one dependant variable at a time. Statistics packages can create cross tabulations to analyze data. It allows decision makes to identify clusters in data.
A common management application of statistical data analysis is in statistical quality control.

8. Forecasting Packages
Forecasting can be defined as predicting the future based on facts known at the present.
The basic steps of time series forecasting.
Pages 224 to 228
One type of forecast is a pure prediction of a phenomenon that will take place in the future. Another type of forecast is derived from a model of how known factors influence other factors that cannot be predicted as easily.
Time series analysis extrapolates a trend solely on its historical changes with no reference to any underlying mechanism that may be responsible for that tend or to a possible relationship between the forecasted item and some other variable. Extrapolation takes the available data,fits a curve to them and extends the curve into the future.
It can be dangerous to trust the output of a forecasting package too much. All forecasts assume that nothing of importance is going to change from the base period to the period being forecasted.
Developing a time series forecast involves three steps:
Determine the periodic cycles of the phenomenon.
Determine the secular trend of the phenomenon.
Determine how much of the historical variation in the phenomenon can be explained by these two factors.

9. Graphing Packages
Most people assimilate data most readily In the form of picture.Most decisions are based on trends or differences that are clearly apparent on a graph.
Page 249
Most spreadsheet,statistical and forecasting packages can produce graphic output. Yet their basic purpose is not graphics, so their capabilities are often limited in this regard. Specialized graphing packages can take their output, in number of standardized interchange formats, and create a variety of charts and graphs with it than the original package could. The need for graphing is dropping as the graphing capabilities of other types of software improve.

10. Programming Languages for DSS
Third generation programming languages.
Fourth generation programming languages.
Pages 229 to 234
Third generation languages have the advantage of standardization. Pascal and C fall under this category. 3GLs have refined codes that utilizes hardware efficiently. High volume transaction processing programs fall under this category. 3GL programming is labor intensive, time consuming and error prone.
The fourth generation languages specifies what the computer should do and not how the computer is to do it. A 4GL like FOCUS uses flexibility and run time efficiency for speed of development. The need to interface to one or more existing databases and to modules written in a 3GL are often important factors in 4GL choice.
4GLs are not widely accepted because:3GLs are designed primarily for applications such as summary reports not complex data manipulation. 3GLs are not standardized. Most existing mainframe based transactions are written in 3GL. The cost of the 4GL and its supporting software is to high.

11. DSS User Interfaces Ten factors to consider DSS user interface design.
Why you should not rely exclusively on color to convey information to DSS user?
Pages 235 to 240
Planning the user interface is an important part of planning any DSS, perhaps more so than with most other types of information systems. DSS users have more sporadic and more varied needs than do most other IS users, and their activities tend to have higher organizational impact. Factors to be considered in planning the DSS user interface include, minimizing task performance time, minimizing learning and recall time, maximizing system versatility, minimizing errors and adapting to different user needs, including the availability of help for those who need it. Additional factors to take into account are the users ability to keep several thing in mind, user fatigue, and command consistency with other systems with which the users are familiar.
Color can often enhance a user interface but must used with due consideration for those users who cannot see a difference among the developers color choices.

12. User Interface Styles The four basic user interface styles.
Pages 240 to 245
There are four general ways to control computers, command liner interfaces , graphical interfaces,, menus, and question and answer dialogues. Each of these applies both to the DSS itself and to the operating system under which the DSS runs.Developing an application that conforms fully to the standards of a GUI is, despite the availability of operating system facilities, more difficult than developing a comparable application that operates via menus and typed in commands.

13. Hypertext/Hypermedia
What is hypertext/hypermedia?
What is virtual reality?
Pages 245 to248
Hypertext refers to electronic document whose parts are electronically linked to avoid limitations of traditional linear media such as bound books. Hypermedia extends to hypertext by adding text , graphics , animation, and sound to electronic document. Together, hypertext and hypermedia allow users to access information as required by their needs rather than by the structure of the database or the limitation of a computer program.
Virtual reality uses hardware and software to give an impression that a computer created environment exists. VR is a step beyond animation. Immerse VR attempts to give the user a sense of inhabiting a computer created space with the ability to manipulate objects in that space.