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Essentials of Systems Analysis and Design Third Edition Joseph S. Valacich Joey F. George Jeffrey A. Hoffer PowerPoint Presentation
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Essentials of Systems Analysis and Design Third Edition Joseph S. Valacich Joey F. George Jeffrey A. Hoffer. Chapter 7 Selecting the Best Alternative Design Strategy. 7.1. Learning Objectives. Learn to assemble the various pieces of an alternative design strategy.

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slide1

Essentials ofSystems Analysis and DesignThird EditionJoseph S. ValacichJoey F. GeorgeJeffrey A. Hoffer

Chapter 7

Selecting the Best Alternative Design Strategy

7.1

Copyright 2006 Prentice-Hall, Inc.

learning objectives
Learning Objectives
  • Learn to assemble the various pieces of an alternative design strategy.
  • Learn how to generate at least three alternative design strategies.
  • Discuss selecting the best design strategy using both qualitative and quantitative methods.

7.2

Copyright 2006 Prentice-Hall, Inc.

learning objectives continued
Learning Objectives (continued)
  • Learn how to use the results of the analysis phase to update a Baseline Project Plan (BPP).

7.3

Copyright 2006 Prentice-Hall, Inc.

selecting the best alternative design strategy
Selecting the Best Alternative Design Strategy
  • Two basic steps:
    • Generate a comprehensive set of alternative design strategies
    • Select the one design strategy that is most likely to result in the desired information system
  • Process:
    • Divide requirements into different sets of capabilities
    • Enumerate different potential implementation environments that could be used to deliver the different sets of capabilities
    • Propose different ways to source or acquire the various sets of capabilities for the different implementation environments

7.4

Copyright 2006 Prentice-Hall, Inc.

selecting the best alternative design strategy continued
Selecting the Best Alternative Design Strategy(continued)
  • Deliverables
    • At least three substantially different system design strategies for building the replacement information system
    • A design strategy judged most likely to lead to the most desirable information system
    • A Baseline Project Plan (BPP) for turning the most likely design strategy into a working information system

7.5

Copyright 2006 Prentice-Hall, Inc.

generating alternative design strategies
Generating Alternative Design Strategies
  • Best to generate three alternatives:
    • Low-End
      • Provides all required functionality users demand with a system that is minimally different from the current system
    • High-End
      • Solves problem in question and provides many extra features users desire
    • Midrange
      • Compromise of features of high-end alternative with frugality of low-end alternative

7.6

Copyright 2006 Prentice-Hall, Inc.

drawing bounds on alternative designs
Drawing Bounds on Alternative Designs
  • Minimum Requirements
    • Mandatory features versus desired features
    • Forms of features
      • Data
      • Outputs
      • Analyses
      • User expectations on accessibility, response time, and turnaround time

7.7

Copyright 2006 Prentice-Hall, Inc.

drawing bounds on alternative designs continued
Drawing Bounds on Alternative Designs (continued)
  • Constraints on System Development:
    • Time
    • Financial
    • Elements of current system that cannot change
    • Legal
    • Dynamics of the problem

7.8

Copyright 2006 Prentice-Hall, Inc.

criteria for choosing off the shelf software
Criteria for Choosing Off-the-Shelf Software
  • Cost
    • In-house versus purchased
  • Functionality
    • Mandatory, essential, and desired features
  • Vendor Support
    • Installation
    • Training
    • Technical support
  • Viability of Vendor

7.9

Copyright 2006 Prentice-Hall, Inc.

criteria for choosing off the shelf software continued
Criteria for Choosing Off-the-Shelf Software (continued)
  • Flexibility
    • Ease of customization
  • Documentation
    • User documentation
    • Technical documentation
  • Response Time
  • Ease of Installation

7.10

Copyright 2006 Prentice-Hall, Inc.

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7.11

Copyright 2006 Prentice-Hall, Inc.

validating purchased software information
Validating Purchased Software Information
  • Information from Vendor
  • Software Evaluation Period
  • Customer References from Vendor
  • Independent Software Testing Service
  • Trade Publications

7.12

Copyright 2006 Prentice-Hall, Inc.

hardware and software issues
Existing Platform

Lower costs

Information system staff is familiar with operation and maintenance

Increased odds of successfully integrating system with existing applications

No added costs of converting old systems to new platform or transferring data

New Hardware and System Software

Some software components will only run on new platform

Developing system for new platform gives organization opportunity to upgrade technology holdings

New requirements may allow organization to radically change its computing operations

Hardware and Software Issues

7.13

Copyright 2006 Prentice-Hall, Inc.

hardware and software issues continued
Hardware and Software Issues (continued)
  • Request for Proposal (RFP)
    • A document provided to vendors to ask them to propose hardware and system software that will meet the requirements of your new system

7.14

Copyright 2006 Prentice-Hall, Inc.

implementation issues
Implementation Issues
  • Technical and social aspects of implementation need to be addressed
  • Training
  • Disruption of Work

7.15

Copyright 2006 Prentice-Hall, Inc.

hoosier burger s new inventory control system
Hoosier Burger’s New Inventory Control System
  • Replacement for existing system
  • Figure 7-4 ranks system requirements and constraints

7.16

Copyright 2006 Prentice-Hall, Inc.

slide17

7.17

Copyright 2006 Prentice-Hall, Inc.

hoosier burger s new inventory control system continued
Hoosier Burger’s New Inventory Control System (continued)
  • Figure 7-5 shows steps of current system
  • When proposing alternatives, the requirements and constraints must be considered

7.18

Copyright 2006 Prentice-Hall, Inc.

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7.19

Copyright 2006 Prentice-Hall, Inc.

hoosier burger s new inventory control system continued20
Hoosier Burger’s New Inventory Control System (continued)
  • Figure 7-7 lists 3 alternatives:
    • Alternative A is a low-end proposal
    • Alternative C is a high-end proposal
    • Alternative B is a midrange proposal

7.20

Copyright 2006 Prentice-Hall, Inc.

hoosier burger s new inventory control system continued21
Hoosier Burger’s New Inventory Control System (continued)
  • Selecting the Most Likely Alternative
    • Weighted approach can be used to compare the three alternatives
    • Figure 7-8 shows a weighted approach for Hoosier Burger
    • Left-hand side of table contains decision criteria
      • Constants and requirements
      • Weights are arrived at by discussion with analysis team, users, and managers
    • Each requirement and constraint is ranked
      • 1 indicates that the alternative does not match the request well or that it violates the constraint
      • 5 indicates that the alternative meets or exceeds requirements or clearly abides by the constraint

7.21

Copyright 2006 Prentice-Hall, Inc.

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7.22

Copyright 2006 Prentice-Hall, Inc.

hoosier burger s new inventory control system continued23
Hoosier Burger’s New Inventory Control System (continued)
  • Selecting the Most Likely Alternative
    • According to the weights used, alternative C appears to be the best choice

7.23

Copyright 2006 Prentice-Hall, Inc.

updating the baseline project plan bpp
Updating the Baseline Project Plan (BPP)
  • The Baseline Project Plan (BPP) was developed during systems planning and selection phase
  • Baseline Project Plan (BPP) can be used as an outline of a status report at analysis phase
  • Schedule will be updated to reflect actual activities and durations
  • An oral presentation of project status is typically made at this phase

7.24

Copyright 2006 Prentice-Hall, Inc.

pvf webstore selecting the best alternative design strategy
PVF WebStore: Selecting the Best Alternative Design Strategy
  • Requirements and constraints were compiled by consultant and team (see Table 7-4)

7.25

Copyright 2006 Prentice-Hall, Inc.

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7.26

Copyright 2006 Prentice-Hall, Inc.

pvf webstore selecting the best alternative design strategy continued
PVF WebStore: Selecting the Best Alternative Design Strategy (continued)
  • Proposed system is a scalable, three-tier approach
    • Scalable
      • The ability to seamlessly upgrade the system through either hardware upgrades, software upgrades or both
    • Three-tier
      • Web Server
        • Provides connection to the Internet and presentation of HTML page
      • Applications Server
        • Middle layer of software and hardware that lies between Web server and corporate network
      • Corporate network
        • Existing organizational computing infrastructure

7.27

Copyright 2006 Prentice-Hall, Inc.

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7.28

Copyright 2006 Prentice-Hall, Inc.

summary
Summary
  • Identify requirements and constraints
  • Generate alternative design strategies
  • Select the best design strategy
  • Update the Baseline Project Plan (BPP)
  • Select the best design strategy for Internet applications

7.29

Copyright 2006 Prentice-Hall, Inc.