Selecting the Best Alternative Design Strategy

1
Chapter 11

• Selecting the Best Alternative Design Strategy

2
Topic Outline

• Analysis Phase
• Alternative Generation and Selection
• Alternative Generation
• System Functionality Alternatives
• Implementation Alternatives
• Acquisition Alternatives
• Alternative Selection

3
Analysis Phase

• Requirements Determination
• Requirements Structuring
• Process Modeling (Ch. 8)
• Logic Modeling (Ch. 9)
• Data Modeling (Ch. 10)
• Alternative Generation and Selection
• 1. Alternative Design Strategy Generation
• 2. Design Strategy Selection

4
Alternative Generation

• Input - Requirements from
• Requirements Gathering - User wants/needs
• Requirements Structuring - Logical process,
  logic, conceptual data models for new system
• Output - Min 3 Alternative Design Strategies
• High-level approach to developing the new IS
• Includes systems functionality, implementation
  environment, and acquisition method

5
System Functionality

• Divide requirements into different sets from
• Required features only (bare bones) to
• All required desired features
• Need to rank/categorize requirements, e.g.,
• Mandatory vs. desired
• Mandatory vs. essential vs. desired
• Also define constraints on IS development
• Implementation Date, Human/ Resources, etc.

6
Implementation Environment

• Hardware/Software Platform Choice
• Run on existing hardware/software platform
• Purchase/upgrade hardware/software platform
• Implementation Issues/Options (see Ch 20)
• Direct Cut-over, Parallel, Phased Implementation
• Training options, etc.
• Organization Issues
• Cost Trade-offs, Mgt Support, User Acceptance
• Assess operational and political feasibility

7
Acquisition Method

• Outsourcing
• Outsiders develop/run application for company
• Outsourcers may have software already
• Purchase software
• Commercial off-the-shelf software (COTS)
• Enterprise solutions (e.g, ERP like SAP, Baan)
• Develop custom software
• Contract with software/consulting firms
• Develop in-house (all or hybrid solution)

8
Alternative Generation

• Alternative System Functionality set
  Implementation option Acquisition method
• Many possible alternatives (e.g., 3 x 2 x 4 24)
• Not all combinations feasible
• Recommend focus on 3 Alternatives
• High-end, Middle, and Low-end Options

9
Alternative Selection

• Identify specific (justifiable selection criteria
• COTS criteria (p. 398)
• Feasibility comparison (Ch. 6)
• Quantitative assessment/ranking (pp. 402-5)
• Analysts recommend design strategy
• Management/Steering Committee decides
• To accept or modify recommendation, or
• Could cancel project

10
Summary

• Alternative generation selection can only be
  performed at end of Analysis Phase, after
  requirements known
• Alternatives are feasible combinations of system
  functionality, implementation acquisition
  options
• Analysts select/justify one alternative, but
  Management decides using its criteria