Determining System
Requirements
Week 4
CMIS570

SDLC
Project Planning
Analysis
Design
Implementation
Support

Requirements Determination
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System requirements
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Functional requirements
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Current and future functions
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Current and future data
Current and future employee jobs

Other requirements to consider
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Technical requirements
Performance requirements
Usability requirements
Reliability requirements
Security requirements

Requirements Structuring
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Three essential views of the current and replacement information systems
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Process view: The sequence of data movement & handling operations within the system
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Data flow diagrams
Logic and timing: Rules by which data are transformed & manipulated & an indication of what triggers data transformation
Structured English, Decision tables, Decision trees, Statetransition diagrams
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Data: The inherent structure of data independent of how or when it is processed
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Entity-relation diagrams

Remember to...

Who will you get info from?
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User Stakeholders
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Users
Managers
Client Stakeholders
Technical Stakeholders

What Information Do You
Need?
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1.
2.
3.

Techniques for Determining
System Requirements
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Review existing documentation
Observation
Interviews
Building a prototype
Questionnaire
JAD

Existing documentation/observation
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Work procedures describe a particular job or task
May show duplication of effort
May find missing steps
May contradict info collected from interviews, questionnaires, and observations
Formal systems vs informal systems

Directly observing users
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Strengths
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Doesn’t rely on a user’s memory
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More objective and accurate than interviews
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Weaknesses
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Hawthorne effect
Time consuming

Conducting interviews

Other things to remember
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Use both open-ended and close-ended questions
Take advantage of follow-up questions, visual cues
Interview in groups

Distribute and collect
Questionnaires
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Strengths
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1.
2.
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3.
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Weaknesses
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1.
2.
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3.

Give Me Ambiguity or Give Me
Something Else!
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How often do you back up your computer files?
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A. Frequently
B. Sometimes
C. Hardly at all
D. Never

This is better…
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How often do you back up the computer files stored on the hard disk on the PC you use for over 50% of your work time?
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A. Frequently (at least once per week)
B. Sometimes (from 1 to 3 times per month)
C. Hardly at all (once per month or less)
D. Never

Modern Methods for Determining
System Requirements
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Prototyping
Joint Application Design (JAD) - Intensive meetings between users, managers, sponsor,
& systems analysts to discuss & review system requirements
Group Support Systems (GSS) to share ideas
& voice opinions
Vendor solutions
CASE tools to analyze existing systems

Structured Walkthroughs
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What is it?
When is it done?
Who is involved?
How is it done?