Determining System Requirements

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Determining SystemRequirements

• Classes 9,10

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SDLC
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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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What Information Do You Need?

• 1.
• 2.
• 3.

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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

• Strengths
• 1.
• 2.
• 3.

• Weaknesses
• 1.
• 2.
• 3.

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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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InterviewsAdvantages Disadvantages

• Strengths
• Extracts both qualitative and quantitative data
• Detailed and summary data
• Good way to find needs and assumptions

• Weaknesses
• Requires skills
• May be biased May collect lots of useless data
• Expensive, time consuming
• Requires other methods to verify results

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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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Find out about someones job

• 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

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Interviewing Groups Adv Disadv

• Strengths
• Not biased by one users opinion
• Can get many users opinion

• Weaknesses
• With many people present, decision-making takes
  time
• Interruptions during process

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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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Directly ObservingUsers

• Strengths
• Doesnt rely on a users memory
• More objective and accurate than interviews

• Weaknesses
• Hawthorne effect
• Time consuming

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Temporary Job Assignment

• Strengths
• Good for learning context, terminology,
  procedures
• Provides insight for other questions
• Get operation feel adds to analysts
  credibility with users

• Weaknesses
• Time Consuming
• May bias future work design towards way things
  are currently done

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Reviewing internal documents

• Strengths
• Good way to learn history and politics
• Explains current context
• May help understand why and way of current
  procedures applications

• Weaknesses
• May bias future work design
• Not useful for obtaining current attitudes or
  motives

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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?