Systems Analysis And Design 2


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Systems Analysis And Design 2

  1. 1. Systems Analysis and Design: The Big Picture Computers:Tools for an Information Age
  2. 2. Objectives <ul><li>Define the terms “system,” “analysis,” and “design” </li></ul><ul><li>Describe the principal functions of the systems analyst </li></ul><ul><li>List and describe the phases of the systems development life cycle </li></ul><ul><li>Describe the various data-gathering and analysis tools </li></ul><ul><li>Describe a selection of systems design tools </li></ul><ul><li>Explain the concept of prototyping </li></ul><ul><li>Explain the role of the maintenance task in the systems development life cycle </li></ul>
  3. 3. Systems Analysis Design <ul><li>System – an organized set of related components established to accomplish a certain task </li></ul><ul><ul><li>Computer system – a system that has a computer as one of its components </li></ul></ul><ul><li>Analysis - Studying an existing system to determine how it works and how it meets users’ needs </li></ul><ul><ul><li>Typically happens as a result of some impetus for change, combined with the authority to make the change </li></ul></ul><ul><li>Design - The process of developing a plan for an improved system, based on the result of the systems analysis </li></ul>
  4. 4. Who Participates? Project Team
  5. 5. Key Individuals Involved in Systems Analysis <ul><li>Systems analyst – performs analysis and design </li></ul><ul><ul><li>May perform some programming as well </li></ul></ul><ul><li>Client – the person or organization contracting to have the work done </li></ul><ul><li>User – the people who will have contact with the system </li></ul>
  6. 6. Systems Analyst: A Change Agent <ul><li>The catalyst or persuader who overcomes the reluctance to change within an organization </li></ul><ul><li>Systems analyst can function as change agent, but it works best if it is someone inside the organization </li></ul><ul><li>What it takes: </li></ul><ul><ul><li>Coordination of many people, tasks, and schedules </li></ul></ul><ul><ul><li>Communication skills, both oral and written </li></ul></ul><ul><ul><li>Planning and design (an analytical mind) </li></ul></ul><ul><ul><ul><li>Self-discipline and self-direction </li></ul></ul></ul><ul><ul><ul><li>Good organizational skills </li></ul></ul></ul><ul><ul><ul><li>Creativity </li></ul></ul></ul><ul><ul><ul><li>The ability to work without tangible results </li></ul></ul></ul>
  7. 7. System Development Life Cycle (SDLC) <ul><li>Organized set of activities that guides those involved through the development of an information system. </li></ul><ul><li>Phases </li></ul><ul><ul><li>Preliminary Investigation </li></ul></ul><ul><ul><li>Analysis </li></ul></ul><ul><ul><li>Design </li></ul></ul><ul><ul><li>Development </li></ul></ul><ul><ul><li>(Documentation) </li></ul></ul><ul><ul><li>Implementation </li></ul></ul><ul><li>Ongoing activities </li></ul><ul><ul><li>Project management </li></ul></ul><ul><ul><li>Overall Documentation </li></ul></ul><ul><ul><li>Information gathering </li></ul></ul>
  8. 8. Systems Development Life Cycle <ul><li>Documentation </li></ul><ul><li>Preliminary Investigation </li></ul><ul><li>Or feasability study </li></ul><ul><li>Problem Definition </li></ul><ul><li>Development and testing. </li></ul><ul><li>Scheduling </li></ul><ul><li>Programming </li></ul><ul><li>Implementation </li></ul><ul><li>Training </li></ul><ul><li>Conversion </li></ul><ul><li>Evaluation </li></ul><ul><li>Maintenance </li></ul><ul><li>Analysis </li></ul><ul><li>Gather data </li></ul><ul><li>Analyze data </li></ul><ul><li>Develop requirements </li></ul><ul><li>Design </li></ul><ul><li>Preliminary design </li></ul><ul><li>Detail design </li></ul><ul><li>Ongoing Activities </li></ul><ul><li>Project Management </li></ul><ul><li>Documentation </li></ul><ul><li>Information Gathering. </li></ul>
  9. 9. System Development Guidelines Use a structured approach Involve the Users Develop Standards
  10. 10. Ongoing Activity: Project Management <ul><li>The process of planning, scheduling, and controlling activities during the SDLC </li></ul><ul><li>Scope (goal, objectives, expectations) </li></ul><ul><li>Activities and Deliverables to be completed </li></ul><ul><li>Time estimates </li></ul><ul><li>Cost estimates </li></ul><ul><li>Order activities occur </li></ul><ul><li>Activities performed concurrently </li></ul>Gantt Chart Project Plan
  11. 11. Ongoing Activity: Feasibility Assessment <ul><li>Measure of how suitable the development of a system will be in the organization. (Initially occurs in the Preliminary Investigation phase but needs to be continuously reevaluated) </li></ul><ul><ul><li>Operational feasibility </li></ul></ul><ul><ul><li>Schedule feasibility </li></ul></ul><ul><ul><li>Technical feasibility </li></ul></ul><ul><ul><li>Economic or cost/benefit feasibility </li></ul></ul>
  12. 12. Ongoing Activity: Documentation <ul><li>Compilation and summarization of data and information </li></ul><ul><ul><li>Reports </li></ul></ul><ul><ul><ul><li>Diagrams </li></ul></ul></ul><ul><ul><ul><li>Programs </li></ul></ul></ul><ul><ul><ul><li>Other deliverables generated during SDLC </li></ul></ul></ul><ul><ul><li>Project Notebook </li></ul></ul><ul><ul><li>Project Dictionary/Repository </li></ul></ul>
  13. 13. Ongoing Activity: Data & Info Gathering <ul><li>Review current system documentation </li></ul><ul><li>Observe </li></ul><ul><li>Send Questionnaires </li></ul><ul><li>Interview </li></ul><ul><ul><li>Structured/Unstructured </li></ul></ul><ul><li>Conduct JAD (joint application design) sessions </li></ul><ul><li>Research </li></ul>Begins in Analysis Phase, but is continually updated
  14. 14. Phase 1: Preliminary Investigation <ul><li>A brief study of the problem to determine whether the project should be pursued </li></ul><ul><ul><li>Also called the feasibility study or system survey </li></ul></ul><ul><ul><li>Involves working with the users </li></ul></ul><ul><ul><li>Organization chart – a hierarchical drawing showing the organization’s management </li></ul></ul>
  15. 15. Feasibility Study <ul><li>Technical feasibility </li></ul><ul><li>Economic feasibility </li></ul><ul><li>Operational feasibility </li></ul><ul><ul><li>are the current work practices and procedures adequate to support the new system? </li></ul></ul><ul><ul><li>Legal feasibility </li></ul></ul><ul><li>Schedule feasibility </li></ul><ul><ul><li>how long will the system take to develop, or can it be done in a desired time-frame? </li></ul></ul>
  16. 16. Defining the Problem <ul><li>Two points that must be agreed upon </li></ul><ul><ul><li>The nature of the problem </li></ul></ul><ul><ul><li>The scope (boundaries) of the problem </li></ul></ul><ul><li>Agreeing on the problem helps define the objectives of the system </li></ul>
  17. 17. Project Request
  18. 18. Feasibility Assessment
  19. 19. Feasibility Assessment (continued)
  20. 20. Phase 2: Analysis <ul><li>Understand the existing system </li></ul><ul><li>Two tasks are involved </li></ul><ul><ul><li>Data gathering </li></ul></ul><ul><ul><li>Data analysis </li></ul></ul>
  21. 21. Data Gathering <ul><li>A number of techniques can be used </li></ul><ul><ul><li>Interviews with users and managers </li></ul></ul><ul><ul><ul><li>Structured interview – includes only questions that have been written out in advance </li></ul></ul></ul><ul><ul><ul><li>Unstructured interview – interviewer has a general goal but few, if any questions prepared </li></ul></ul></ul><ul><ul><li>Examining current business and systems documents and output </li></ul></ul><ul><ul><ul><li>may include current order documents, computer systems procedures and reports used by operations and senior management </li></ul></ul></ul><ul><ul><li>Sending out questionnaires </li></ul></ul><ul><ul><li>Observation of current procedures </li></ul></ul><ul><ul><ul><li>by spending time in various departments; a time and motion study can show where procedures could be more efficient, or to detect bottlenecks </li></ul></ul></ul>
  22. 22. Data Analysis <ul><li>Typical tools for data analysis </li></ul><ul><ul><li>Entity Relationship diagram </li></ul></ul><ul><ul><li>Data flow diagram </li></ul></ul><ul><ul><li>Decision table/Decision Tree </li></ul></ul><ul><ul><li>Written report </li></ul></ul><ul><li>Report to management/ customer/ client </li></ul>
  23. 23. Entity-Relationship Diagrams (ERD) <ul><li>Tool to graphically represent the associations between entities in the project </li></ul>Noun Verb
  24. 24. Data Flow Diagrams (DFD) <ul><li>Tool to graphically represent the </li></ul><ul><li>flow of data in a system </li></ul>Process Source Data Flow Data Store
  25. 25. Decision Table Decision Tree
  26. 26. System Requirements & recommendations <ul><li>A detailed list of things the system must be able to do </li></ul><ul><ul><li>Highlight problems with current system </li></ul></ul><ul><ul><li>The design of the new system will be based on these requirements </li></ul></ul><ul><ul><li>Analyst and management must come to a clear agreement on requirements </li></ul></ul><ul><ul><li>List of possible solutions </li></ul></ul><ul><ul><li>Hardware/software recommendations </li></ul></ul>
  27. 27. Report to Management <ul><li>Summarizes the problems found in the current system </li></ul><ul><li>Describes the requirements for the new system, including a cost analysis </li></ul><ul><li>Makes a recommendation on what course to take next </li></ul>
  28. 28. Pre-Design considerations <ul><li>The hardware platform </li></ul><ul><ul><li>which type of computer, network capabilities, input, storage and output devices </li></ul></ul><ul><li>The software </li></ul><ul><ul><li>programming language, package or database </li></ul></ul><ul><li>The outputs </li></ul><ul><ul><li>report layouts and screen designs </li></ul></ul><ul><li>The inputs </li></ul><ul><ul><li>documents, screen layouts, validation procedures </li></ul></ul><ul><li>The user interface </li></ul><ul><ul><li>how users will interact with the computer system </li></ul></ul><ul><li>The modular design </li></ul><ul><ul><li>of each program in the application </li></ul></ul><ul><li>The test plan and test data </li></ul><ul><li>Conversion plan </li></ul><ul><ul><li>how the new system is to be implemented </li></ul></ul><ul><li>Documentation </li></ul><ul><ul><li>User </li></ul></ul><ul><ul><li>Technical </li></ul></ul>
  29. 29. Phase 3: Design <ul><li>The new system is actually planned </li></ul><ul><li>Divided into two subphases </li></ul><ul><ul><li>Preliminary design </li></ul></ul><ul><ul><ul><li>Several key decisions must be made </li></ul></ul></ul><ul><ul><li>Detail design specifications </li></ul></ul><ul><ul><ul><li>Output requirements </li></ul></ul></ul><ul><ul><ul><li>Input requirements </li></ul></ul></ul><ul><ul><ul><li>Files and databases </li></ul></ul></ul><ul><ul><ul><li>System processing </li></ul></ul></ul><ul><ul><ul><li>System controls and backups </li></ul></ul></ul>
  30. 30. Build or Buy? <ul><li>Custom Software </li></ul><ul><ul><li>Developed by user </li></ul></ul><ul><ul><li>Developed at user request by outside vendor </li></ul></ul><ul><li>Packaged Software </li></ul><ul><ul><li>Horizontal </li></ul></ul><ul><ul><ul><li>Many org types </li></ul></ul></ul><ul><ul><li>Vertical </li></ul></ul><ul><ul><ul><li>Industry specific </li></ul></ul></ul>Preliminary
  31. 31. Acquire Hardware/Software <ul><li>Technical specifications </li></ul><ul><li>Solicit vendor proposals </li></ul><ul><li>Test & evaluate </li></ul><ul><ul><li>Benchmark Test </li></ul></ul><ul><li>Make a decision </li></ul>Detail
  32. 32. Input Output <ul><li>Things to consider </li></ul><ul><ul><li>The medium (paper, screen, etc.) of the output </li></ul></ul><ul><ul><li>The types of reports needed and what data is needed for the reports </li></ul></ul><ul><li>Things to consider </li></ul><ul><ul><li>The input medium (captured at the source, keyed from source document) </li></ul></ul><ul><ul><li>The fields needed, how they are laid out on the input screen, etc. </li></ul></ul><ul><ul><li>Input validation may be necessary </li></ul></ul>Detail Requirements
  33. 33. Input/Output Design Mockup (User) Layout Chart (Programmer)
  34. 34. Files and Databases <ul><li>Things to consider </li></ul><ul><ul><li>How files are organized </li></ul></ul><ul><ul><ul><li>Sequentially, directly, or by another method </li></ul></ul></ul><ul><ul><li>The format of the records making up the data files </li></ul></ul>Detail
  35. 35. Database Design <ul><li>Table structure definitions & relationships </li></ul><ul><li>Security </li></ul>Detail
  36. 36. Program Design Data Entry Program File Hard copy Comment Flow Chart System Processing Detail
  37. 37. Phase 4: Development <ul><li>Schedule and monitor the two principal activities </li></ul><ul><ul><li>Programming </li></ul></ul><ul><ul><li>Testing </li></ul></ul><ul><li>There are several project scheduling tools available </li></ul>
  38. 38. Programming <ul><li>Prepare program design specifications </li></ul><ul><li>Use logic flowcharts and pseudocode to facilitate code development </li></ul>
  39. 39. Testing <ul><li>Unit testing – verifies that individual program units work </li></ul><ul><ul><li>Perform testing with test data </li></ul></ul><ul><li>System testing – determines whether all program units work together as planned </li></ul><ul><li>Volume testing – uses real data in large amounts </li></ul><ul><ul><li>Determines whether the system can handle a large volume of data </li></ul></ul>
  40. 40. Phase 5: Implementation <ul><li>Steps involved in starting the new system </li></ul><ul><ul><li>Training </li></ul></ul><ul><ul><li>Equipment conversion </li></ul></ul><ul><ul><li>File conversion </li></ul></ul><ul><ul><li>System conversion </li></ul></ul><ul><ul><li>Auditing </li></ul></ul><ul><ul><li>Evaluation </li></ul></ul><ul><ul><li>Maintenance </li></ul></ul>
  41. 41. Training <ul><li>Teach users how to use the system </li></ul><ul><ul><li>The system will do no better than the people using it </li></ul></ul><ul><ul><li>Develop user’s manual to aid users who are not familiar with the system </li></ul></ul><ul><ul><li>Hands-on training is best </li></ul></ul>
  42. 42. Equipment Conversion <ul><li>Items to consider </li></ul><ul><ul><li>Delivery schedules must be coordinated </li></ul></ul><ul><ul><li>Terminals or personal computers must be networked </li></ul></ul><ul><ul><li>Devices on the system must be compatible </li></ul></ul>
  43. 43. File Conversion <ul><li>If existing files are manual, they must be keyed in or scanned into the system </li></ul><ul><ul><li>Manual files must be kept current while data is being input into the new system </li></ul></ul><ul><li>If existing files are computer-based, programs must be written to convert the files into the format needed for the new system </li></ul>
  44. 44. System Conversion <ul><li>Four approaches </li></ul><ul><ul><li>Direct conversion – the user simply stops using the old system and starts using the new one </li></ul></ul><ul><ul><li>Phased conversion – the system is implemented one part at a time </li></ul></ul><ul><ul><li>Pilot conversion – the entire system is used by a designated set of users </li></ul></ul><ul><ul><li>Parallel conversion – the old and new systems are both used until users are satisfied the new system works </li></ul></ul>
  45. 45. Conversion Options
  46. 46. Auditing <ul><li>Systems to trace data in the system back to a source document </li></ul><ul><ul><li>Very helpful in tracing security violations </li></ul></ul>
  47. 47. Evaluation <ul><li>Determines how well the system is meeting the original requirements, benefits, and budgets </li></ul><ul><ul><li>Evaluation can be performed by the analyst and someone from the organization </li></ul></ul><ul><ul><li>Evaluation can also be performed by an independent third party </li></ul></ul>
  48. 48. Maintenance <ul><li>An ongoing activity that lasts the lifetime of the system </li></ul><ul><li>Several types of maintenance activities </li></ul><ul><ul><li>Enhancements to the system </li></ul></ul><ul><ul><li>Fix bugs in the system as they are identified </li></ul></ul>
  49. 49. Terms to Know: Chapter 14 <ul><li>Analysis </li></ul><ul><li>Benchmark test </li></ul><ul><li>Build-or-buy decision </li></ul><ul><li>CASE </li></ul><ul><li>Cost/benefit analysis </li></ul><ul><li>Data dictionary </li></ul><ul><li>Data flow diagram </li></ul><ul><li>Decision tree/Decision table </li></ul><ul><li>Deliverable </li></ul><ul><li>Design </li></ul><ul><li>Development </li></ul><ul><li>Direct conversion </li></ul><ul><li>Documentation </li></ul><ul><li>Entity-relationship diagram (ERD) </li></ul><ul><li>Feasibility Assessment/Study </li></ul><ul><li>Gantt chart </li></ul><ul><li>Joint application development (JAD) </li></ul><ul><li>Layout chart </li></ul><ul><li>Mockup </li></ul><ul><li>Outsourcing </li></ul><ul><li>Parallel conversion </li></ul><ul><li>Phased conversion </li></ul><ul><li>Pilot conversion </li></ul><ul><li>Post-implementation system review </li></ul><ul><li>Preliminary investigation </li></ul><ul><li>Project dictionary </li></ul><ul><li>Project plan </li></ul><ul><li>Prototype </li></ul><ul><li>RFP, RFQ, RFI </li></ul><ul><li>Scope </li></ul><ul><li>System </li></ul><ul><li>System design </li></ul><ul><li>System development life cycle-SDLC </li></ul><ul><li>System testing </li></ul><ul><li>Systems analyst </li></ul><ul><li>Unit testing </li></ul><ul><li>Volume testing </li></ul>
  50. 50. If asked, can you… <ul><li>Define the terms “system,” “analysis,” and “design” </li></ul><ul><li>Describe the principal functions of the systems analyst </li></ul><ul><li>List and describe the phases of the systems development life cycle </li></ul><ul><li>Describe the various data-gathering and analysis tools </li></ul><ul><li>Describe a selection of systems design tools </li></ul><ul><li>Explain the concept of prototyping </li></ul><ul><li>Explain the role of the maintenance task in the systems development life cycle </li></ul>
  51. 51. Sources <ul><li>Capron; Computers: Tools for An Information Age, 8 th Ed. 2003 </li></ul><ul><li>Pfaffenberger; Computers in Your Future 2003 </li></ul><ul><li>Microsoft Clipart </li></ul>