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DSS Software Tools

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User-Interface Styles. DSS Software Categories. Three Basic Database Structure ... referred by row and column names instead of letter-and-number references ... – PowerPoint PPT presentation

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Title: DSS Software Tools


1
DSS Software Tools
  • Adopted by
  • Dr. Adel S. Aldosary
  • for CRP 507, April 27,29, 2003

2
Agenda
  • Review Last Lecture
  • User-Interface Styles
  • DSS Software Categories
  • Three Basic Database Structure
  • Specialized Modeling Languages
  • Video

3
DSS Software Categories
  • purchase a turnkey package
  • customize a package
  • use specialized tools or generators
  • custom software
  • program from scratch in a suitable language

4
Standard Packages
  • help make specific and common decisions
  • potential market is large
  • decision of financial importance to people
  • underlying factors the same for everyone
  • e.g., price-earning ratio/chart of companies
  • support infrastructure already exists
  • e.g., public databases that provide necessary
    data to anyone for a small fee

5
Specialized Tools and Generators
  • Standardized building blocks for DSS dev.
  • Major categories
  • database management packages
  • information retrieval (query reporting)
    packages
  • specialized modeling packages (including
    spreadsheets) and languages
  • statistical data analysis packages
  • forecasting packages
  • graphics packages

6
Database Management Systems (DBMS)
  • a database collection of files
  • allow users to store data in an organized form
    and retrieve it on the basis of specified
    selection criteria
  • ability to integrate data from several files

7
Database (DB)
  • Reflects a conceptual data model
  • e.g., Entity-relationship diagram (ERD)
  • - specifies the entities about which the database
    contains data and the way in which these entities
    are related

8
Three Basic Database Structures
  • Hierarchical DB model
  • link records of different types in a strict
    hierarchy from top to bottom
  • Network DB model
  • provide more flexibility than hierarchical DB
    structure in the way different files are linked
  • Relational DBMS
  • stores data in the form of 2-dimensional tables
  • e.g., Microsoft Access DB4

9
Relational Database Management
  • Link records from several tables by matching
    corresponding fields
  • Return the set of all records satisfying a given
    set of conditions specified in the retrieval
    operations
  • Standardization of interface
  • SQL (Structured Query Language)

10
Information Retrieval Packages
  • Included as part of a DBMS-based system or sold
    separately
  • Overcome difficulties inherent in end-user
    attempts to access a database via SQL
  • Strength of a good information retrieval package
  • power ability to specify complex queries
  • ease of use master the package in a short time
  • e.g., graphically oriented info. retrieval
    packages

11
Specialized Modeling Languages
  • Packages do not incorporate models themselves,
    but simply make it easier for users to define the
    characteristics of models
  • Accounting models a static model with no
    uncertainty
  • spreadsheet 2 dimensional grid of cells
  • IFPS (Interactive Financial Planning System)
  • model exists as a separate, easily visible, and
    easily auditable entity from data

12
Spreadsheets
  • Numbers, text, or formulas in cells
  • Examples
  • built-in functions for mathematical and business
    computations NPV calculations, statistics, etc.
  • conditional computation capabilities
  • graphs
  • extend 2-dimensional grid to 3 or more dimensions
  • treat contents of each row as a simple database
  • formatting capability

13
Drawbacks of Spreadsheets
  • Potential for errors
  • Formulas normally hidden from user and scattered
    all over the spreadsheet
  • Susceptible to malicious change by users

14
IFPS
  • Software developed specifically for financial
    modeling
  • Data and models are separate entities
  • easier to identify errors
  • easier to audit

15
Features of IFPS
  • Output cells referred by row and column names
    instead of letter-and-number references
  • Formulas apply to entire row (unless otherwise
    stated)
  • Backward reference uses the word previous
    instead of obscure cell reference
  • Include goal seeking, what-if testing of
    alternatives, and a full set of financial and
    mathematical functions

16
Statistical Data Analysis Packages
  • Premise future is in some way tied to factors we
    can change
  • Simplest type of prediction
  • regression calculations
  • develop formula for prediction
  • determine correlation (between estimating formula
    and dependent variable) to what degree is the
    dependent variable accounted for by the variables
    considered

17
Common Features of Statistical Packages
  • Forecasting methods
  • Time-series analysis
  • Regression and variance analysis
  • Multivariate analysis
  • Spectral analysis
  • Tools for econometric modeling
  • Optimization methods for OM
  • Variety of graphical output method
  • Extension data access capability for DBMS

18
Forecasting Packages
  • Forecasting
  • predicting a phenomenon that will take place in
    the future
  • e.g., forecast customer order weather forecast
  • model how known factors influence other factors
  • e.g., economics models
  • example of a forecasting problem
  • time series forecast

19
Graphing or Charting Packages
  • People assimilate data most readily in the form
    of a picture
  • Graphs cannot convey differences among numbers
    smaller than 1 percent of their full scale such
    precision usually not required in decision
    support applications
  • Many problems/decisions are based on
    trends/differences that are clearly apparent on a
    graph

20
Programming Languages for DSS
  • Writing a DSS from scratch
  • Third Generation Programming Languages (3GL)
  • procedural efficient in run-time
  • take a longer time to develop than 4GL
  • labor intensive, time consuming, error prone
  • Fourth Generation Programming Languages (4GL)

21
Fourth Generation Languages (4GL)
  • Specify what the computer is to do, not how the
    computer is to do it
  • Trading off flexibility and run-time efficiency
    for speed of development
  • Shorter application development by an order of
    magnitude
  • Quicker to modify DSS to react to changing
    conditions

22
Why is 4GL not widely used?
  • Most existing systems are written in COBOL (3GL)
  • More trained and experienced 3GL programmers
  • 4GLs are not standardized, unlike 3GLs
  • differences among 4GLs
  • similarities among 3GLs
  • concern with run-time efficiency
  • cost of 4GL and its supporting software
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