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Chapter 4 Requirement Modeling

Chapter 4 Requirement Modeling. Phase Description. Systems analysis is the second of five phases in the systems development life cycle (SDLC) Uses requirements modeling and data and process modeling to represent the new system

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Chapter 4 Requirement Modeling

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  1. Chapter 4Requirement Modeling

  2. Phase Description • Systems analysis is the second of five phases in the systems development life cycle (SDLC) • Uses requirements modeling and data and process modeling to represent the new system • Before proceeding to the next phase, systems design, you will consider system development strategies

  3. Systems Analysis Phase Overview • Systems Analysis Activities • Requirements modeling • Data and process modeling • Object modeling • Development Strategies

  4. Introduction • This chapter describes requirements modeling techniques and team-based methods that systems analysts use to visualize and document new systems • Fact-finding techniques include interviewing, documentation review, observation, surveys and questionnaires, sampling, and research

  5. Systems Analysis Phase Overview • The overall objective is to understand the proposed project, ensure that it will support business requirements, and build a solid foundation for system development • You use models and other documentation tools to visualize and describe the proposed system

  6. Systems Analysis Phase Overview • Systems Analysis Skills • Analytical skills • Interpersonal skills • Team-Oriented Methods and Techniques • Joint application development (JAD) • Rapid application development (RAD) • Agile methods

  7. Joint Application Development • User Involvement • Users have a vital stake in an information system, and they should participate fully • Successful systems must be user-oriented and users need to be involved

  8. Joint Application Development • JAD Participants and Roles • JAD participants should be insulated from the distraction of day-to-day operations • Objective is to analyze the existing system, obtain user input and expectations, and document user requirements for the new system

  9. Joint Application Development • JAD Participants and Roles Figure 3-4

  10. Joint Application Development Figure 3-5

  11. Joint Application Development • JAD Advantages and Disadvantages • Advantages • Allows key users to participate effectively • Disadvantages • More expensive and can be cumbersome if the group is too large relative to the size of the project

  12. Rapid Application Development • Rapid application development (RAD) is a team-based technique that speeds up information systems development and produces a functioning information system • RAD uses a group approach, but goes much further • The end product of RAD is the new information system

  13. Rapid Application Development • RAD Phases and Activities

  14. Rapid Application Development • RAD Advantages and Disadvantages • Advantages • Systems can be developed more quickly with significant cost savings • Disadvantages • RAD stresses the mechanics of the system itself and does not emphasize the company’s strategic business needs • Might allow less time to develop quality, consistency, and design standards

  15. Agile Methods • Attempt to develop a system incrementally • Agile Method Advantages and Disadvantages • Are very flexible and efficient in dealing with change • Frequent deliverables constantly validate the project and reduce risk • Team members need a high level of technical and interpersonal skills • May be subject to significant change in scope

  16. Modeling Tools and Techniques • CASE Tools • Functional Decomposition Diagrams • Data Flow Diagrams • Unified Modeling Language

  17. Modeling Tools and Techniques • CASE Tools • Offer powerful modeling features • Systems analysts use modeling and fact-finding interactively • Functional Decomposition Diagrams • Functional decomposition diagram (FDD)

  18. Modeling Tools and Techniques • Functional Decomposition Diagrams Figure 3-9

  19. Data Flow Diagrams

  20. System Requirements Checklist • System requirement • After gathering information about new system, system analyst needs to describe all system requirements. • A feature that must be included in an IS to satisfy business requirement and be acceptable to users. • Five general categories • Outputs • Inputs • Processes • Performance • Controls

  21. System Requirements Checklist • Outputs • 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 parts — sorted by part number

  22. System Requirements Checklist • Inputs • Manufacturing employees must swipe their ID cards(刷卡)into online data collection terminals that record labor costs and calculate production efficiency • The department head must enter overtime hours on a separate screen

  23. System Requirements Checklist • Processes • 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

  24. System Requirements Checklist • Performance • The system must support 25 users online simultaneously • Response time must not exceed four seconds

  25. System Requirements Checklist • Controls • The system must provide log-on 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

  26. Future Growth, Costs, and Benefits • Scalability(擴展性) • A scalable system offers a better return on the initial investment • To evaluate, you need information about projected future volume for all outputs, inputs, and processes

  27. Future Growth, Costs, and Benefits • Total Cost of Ownership • Total cost of ownership (TCO) is especially important if the development team is evaluating several alternatives • One problem is that cost estimates tend to understate indirect costs

  28. Fact-Finding • Fact-Finding Overview • The first step is to identify the information you need • Who, What, Where, When, How, and Why? • Difference between asking what is being done (current situation) and what could or should be done (future improvement) • Know now first, and future comes later

  29. Fact-Finding • Who, What, Where, When, How, and Why? Figure 3-15

  30. Interviews • Systems analysts spend a great deal of time talking with people • Much of that time is spent conducting interviews • Consists of 7 steps

  31. Interview • Step 1: Determine the People to Interview • Informal structures: some people have more influence or knowledge than appears on an organization chart. • Step 2: Establish Objectives for the Interview • Determine the general areas to be discussed • List the facts you want to gather

  32. Interviews • Step 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 How is the task performed? • Closed-ended questions How many pc do you have in this department? • Range-of-response questions On a scale of 1 to 10, how effective was your training?

  33. Interviews • Step 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 • Ask the interviewee to have samples available

  34. Interviews Figure 4-19

  35. Interviews Figure 4-20

  36. Interviews • Step 5: Conduct the Interview • Develop a specific plan for the meeting • Begin by introducing yourself, describing the project, and explaining interview objectives • Use engaged listening • Allow the person enough time to think about the question • Summarize main points • After interview, summarize the session and seek a confirmation

  37. Interviews • Step 6: Document the Interview • During the interview, note taking should be kept to a minimum • After the interview, record the information quickly • 50% of a conversation is forgotten within 30 minutes • After the interview, send memo expressing appreciation, including the main points discussed so the interviewee has a written summary and can offer additions or corrections

  38. Interviews • Step 7: Evaluate the Interview • In addition to recording the facts obtained in an interview, try to identify any possible biases • Unsuccessful Interviews • No matter how well you prepare for interviews, some are not successful

  39. Other Fact-Finding Techniques • Document Review • Observation • Seeing the system in action gives you additional perspective and a better understanding of the system procedures • Plan your observations in advance • Hawthorne Effect

  40. 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

  41. Other Fact-Finding Techniques • Sampling • Systematic sample • Stratified (分層的)sample • Random sample • Main objective of a sample is to ensure that it represents the overall population accurately

  42. Other Fact-Finding Techniques • Research • Newsgroups • Site visit

  43. Other Fact-Finding Techniques • Interviews versus Questionnaires • Interview is more familiar and personal • Questionnaire gives many people the opportunity to provide input and suggestions • Brainstorming • Structured brainstorming (take turn to speak) • Unstructured brainstorming (speak when you have an idea)

  44. Documentation • The Need for Recording the Facts • Record information as soon as you obtain it • Use the simplest recording method • Record your findings in such a way that they can be understood by someone else • Organize your documentation • Some useful methods: DFD, flowcharts, sample forms, and screen captures

  45. Documentation • Software Tools • CASE Tools • Productivity Software • Word processing, spreadsheets, database management, presentation graphics, histogram

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