Lecture 3: Requirements Analysis Problem Definition

1
Lecture 3Requirements AnalysisProblem
Definition
2
Typical IS Problems

• Relevancy (Decision making)
• Accuracy
• correctness
• completeness
• security
• Timeliness

3
Typical IS Problems

• Economy ()
• Efficiency
• Output / Input
• Reliability
• Variance rather than Mean
• Usability
• Human Factors / Ergonomics

4
Analysis

• A. Determine system requirements
• B. Structure requirements
• 1. Process modeling
• 2. Logic modeling
• 3. Data modeling
• C. Select best alternative

5
Requirements Analysis Goals

• Fully describe the current system
• Study and analyze the current system (gather and
  study facts)
• Determine the ideal information system
• Identify resource constraints
• Define and prioritize requirements
• Inspire user confidence/ownership

6
Study Analyze Current System

• Gather information on what the system should do
  from as many sources as possible
• Concentrate on WHAT is needed, not HOW to do it
• Dont try to fix it unless you understand it
• Major problem analyst not understanding user
  needs

7
Study Analyze Current System

• -- Activities --
• 1. Learn about current system (gather facts)
• 2. Model current system
• 3. Analyze problems/opportunities (study facts)
• 4. Establish new system objectives

8
Study Analyze Current System
-- Output -- 1. Complete statement of user
environment 2. Models of current system 3. List
of major problems/causes/effects 4. System
objectives
9
Learn About Current System (gather facts)

• Gather information from
• Current information system
• a current IS may exist
• External sources
• reviewing other IS outside the organization can
  reveal practical ideas and techniques
• Internal sources
• single most important source of facts is the user
• existing paper work or documents is also a good
  source

10
Tactics

• Listen - dont lecture
• Dont pre-solve problem
• Compare stories
• Look for reluctant responses
• Observe your effects on system
• Avoid politics (head nodding)
• Expect hard, boring work

11
Fact-finding Methods

• Research and site visits
• Existing documentation
• Observation
• Questionnaires
• Interviews

12
Establish New System Objectives

• Objective a measure of success
• Should be precise, measurable statements of
  business performance
• Be careful not to state requirements as
  objectives
• Experience is the best teacher

13
User Requirements

• User system objectives (unedited)
• Reports (type/frequency)
• User training needs
• Effect of system on various users
• Organization Chart

14
System Constraints

• Time
• Skills
• Funds
• Technology
• External factors

15
Documentation

• Data collection instruments
• DFDs
• Other