Transcript
Systems Analysis and Design
CIS 2303
Part 3
An extension to Learning Outcome 2:
SDLC: Analysis Phase (Requirement Modeling) – Ch4
Lecture Objectives
1. Understand importance of requirements
2. Identify Requirements
3. Fact-finding techniques
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Importance of Systems RequirementSystems Requirements is a feature
that must be included in order for the system to be acceptable to users.
Two categories: 1) Functional requirements describe activities or processes the system must perform (e.g., calculate payroll taxes). 2) Technical requirements describe an operating environment or performance objective (e.g., must run with UNIX or must have one-half second response time).
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Identify System Requirements
Systems Analysis Activities◦Requirements modeling has the
following categories:
Outputs InputsProcessesPerformanceControls
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System Requirements ChecklistOutputs
Examples:- The Web site must report online volume
statistics every four hours, and hourly during peak periods
- The inventory system must produce a daily report showing the part number, description, quantity on hand, quantity allocated, quantity available, and unit cost of all sorted by part number
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System Requirements ChecklistInputs
Examples:- The department head must enter
overtime hours on a separate screen- Student grades must be entered on
machine-scannable forms prepared by the instructor.
- Each input form must include date, time, product code, customer number, and quantity
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System Requirements ChecklistProcesses
Examples:- The student records system must calculate the GPA at the end of each semester
- As the final step in year-end processing, the payroll system must update employee salaries, bonuses, and benefits and produce tax data required by the IRS
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System Requirements ChecklistPerformance
Examples:-The system must support 25 users online simultaneously
- Response time must not exceed four seconds
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System Requirements ChecklistControls
Examples:
- The system must provide logon security at the operating system level and at the application level
- An employee record must be added, changed, or deleted only by a member of the human resources department
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Future Growth, Costs, and BenefitsScalability Why?:
◦A scalable system offers a better return on the initial investment
◦To evaluate scalability, you need information about projected future volume for all outputs, inputs, and processes
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In-Class Exercise
Study the DWC “Portal System” and give one example to each of the following:◦Inputs
◦Outputs
◦Processes
◦Performance
◦Control
Fact-FindingFact-Finding Overview
◦First, you must identify the information you need
◦Develop a fact-finding planWho, What, Where, When, How,
and Why?◦Difference between asking what is
being done and what could or should be done
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InterviewsStep 1: Determine the People to
Interview◦Informal structures
Step 2: Establish Objectives for the Interview◦Determine the general areas to be
discussed◦List the facts you want to gather
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InterviewsStep 3: Develop Interview
Questions◦Creating a standard list of interview
questions helps to keep you on track and avoid unnecessary tangents
◦Avoid leading questions◦Open-ended questions◦Closed-ended questions◦Range-of-response questions
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InterviewsStep 4: Prepare for the Interview
◦Careful preparation is essential because an interview is an important meeting and not just a casual chat
◦Limit the interview to no more than one hour
◦Send a list of topics
Step 5: Conduct the Interview◦Develop a specific plan for the
meeting 15
Interviews• Step 6: Document the Interview
–Note taking should be kept to a minimum–Note date, time, location, purpose of the
interview, and the main points you discussed so the interviewee has a written summary and can offer additions or corrections
Step 7: Evaluate the Interview◦In addition to recording the facts obtained
in an interview, try to identify any possible biases
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Other Fact-Finding Techniques• Document
Review
• Observation– Seeing the system
in action gives you additional perspective and a better understanding of the system procedures
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Other Fact-Finding Techniques
Questionnaires and Surveys◦ When designing a
questionnaire, the most important rule of all is to make sure that your questions collect the right data in a form that you can use to further your fact-finding
◦ Fill-in form
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Other Fact-Finding TechniquesSampling
◦Systematic sample◦Stratified sample◦Random sample◦Main objective of a sample is to
ensure that it represents the overall population accurately
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Other Fact-Finding Techniques
Research◦ Can include the
Internet, IT magazines, and books to obtain background information, technical material, and news about industry trends and developments
◦ Site visit
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Other Fact-Finding TechniquesInterviews versus Questionnaires
◦Interview is more familiar and personal
◦Questionnaire gives many people the opportunity to provide input and suggestions
◦Brainstorming
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Review Questions:What are the five questions typically used in
fact-finding? What additional question can be asked during this process? refer to (Page 157)
What is a systems requirement, and how
are systems requirements classified? refer to (Page 153)
What are three types of sampling, and why would you use them? refer to (Page 167-168)
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