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Determining System Requirements. Classes 9,10. SDLC. Project Identification & Selection. Project Initiation & Planning. Analysis **. Logical Design. Physical Design. Implementation. Maintenance. Requirements Determination. System requirements Functional requirements

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Determining system requirements l.jpg

Determining SystemRequirements

Classes 9,10

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Project Identification

& Selection

Project Initiation

& Planning



Logical Design

Physical Design



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Requirements Determination

  • System requirements

    • Functional requirements

      • Current and future functions

      • Current and future data

      • Current and future employee jobs

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Requirements Structuring

  • Two essential views of the current and replacement information systems. Both are describing the same system, but in a different way.

    • Process view: The sequence of data movement & handling operations within the system

      • Data flow diagrams

    • Data: The inherent structure of data independent of how or when it is processed

      • Entity-relation diagrams

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Remember to...

Assume Anything is Possible

Question Everything

Pay Attention to Details

Don't Jump to Conclusions

Be Impartial

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Who will you get info from?

  • User Stakeholders

    • Users

    • Managers

  • Client Stakeholders

  • Technical Stakeholders

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Traditional Methods for Determining System Requirements

  • Administering questionnaires

  • Interviewing and listening

  • Interviewing groups

  • Directly observing users

  • Analyzing procedures & other documents

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Administering QuestionnairesAdvantages & Disadvantages

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Give Me Ambiguity or Give Me Something Else!

  • How often do you back up your computer files?

    • A. Frequently

    • B. Sometimes

    • C. Hardly at all

    • D. Never

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This is better…

  • 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?

    • 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

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Interviewing & Listening

  • Before

  • During the interview

  • Afterwards

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During the Interview

  • Beginning

    • Introduction, open-ended questions, interest & attention

  • Middle

    • Open & close-ended questions, f-u questions, active listening, provide feedback, limit note-taking

  • End

    • Summarize, request feedback and/or f-u, ask for corrections

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Extracts both qualitative and quantitative data

Detailed and summary data

Good way to find needs and assumptions


Requires skills

May be biased; May collect lots of useless data

Expensive, time consuming

Requires other methods to verify results

InterviewsAdvantages & Disadvantages

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How do you choose interview questions?

  • Open-ended questions

    • 1.

    • 2.

    • 3.

  • Closed-ended questions

    • 1.

    • 2.

    • 3.

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Write 3 open-ended questions

Ask 3 open-ended questions (You may substitute questions during interview.)

Write down answers

Write 3 closed-ended questions

Ask 3 closed-ended questions (You may substitute questions during interview.)

Write down answers

Find out about someone’s job

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Not biased by one user’s opinion

Can get many user’s opinion


With many people present, decision-making takes time

Interruptions during process

Interviewing Groups Adv & Disadv

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You May Need to Analyze Work Procedures

  • 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

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Doesn’t rely on a user’s memory

More objective and accurate than interviews


Hawthorne effect

Time consuming

Directly ObservingUsers

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Good for learning context, terminology, procedures

Provides insight for other questions

Get operation “feel”; adds to analysts credibility with users


Time Consuming

May bias future work design towards way things are currently done

Temporary Job Assignment

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Good way to learn history and politics

Explains current context

May help understand why and way of current procedures & applications


May bias future work design

Not useful for obtaining current attitudes or motives

Reviewing internal documents

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Modern Methods for Determining System Requirements

  • 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

  • BPR – Business process reengineering

  • CASE tools to analyze existing systems

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Structured Walkthroughs

  • What is it?

  • When is it done?

  • Who is involved?

  • How is it done?