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Systems Analysis and Design

Systems Analysis and Design. Objectives. Define the terms system, analysis, and design Describe the principal functions of the systems analyst List and describe the phases of the systems development life cycle Describe the various data gathering and analysis tools

sarah-fitzgerald
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Systems Analysis and Design

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  1. Systems Analysis and Design

  2. Objectives • Define the terms system, analysis, and design • Describe the principal functions of the systems analyst • List and describe the phases of the systems development life cycle • Describe the various data gathering and analysis tools • Describe a selection of systems design tools • Explain the concept of prototyping • Explain the role of the maintenance task in the systems development life cycle

  3. Contents • What is Systems Analysis and Design? • Systems Analyst • Systems Development Life Cycle • Preliminary Investigation • Analysis • Design • Development • Implementation

  4. Systems Analysis and Design What is it? • System • organized set of related components established to accomplish certain task • Natural • Planned and placed by people • Computer system • A system that has computers as one of its components

  5. Systems Analysis and Design What is it? • Systems analysis Process of studying an existing system to determine how it works and how it meets user needs • Systems design Process of developing a plan for an improved system, based upon the results of the systems analysis

  6. Systems Analysis and Design Why do it? • Impetus for change • Internal force • External force • Authority for change • Approval of higher management

  7. Systems Analyst • Professional computer employee who performs analysis and design • Change agent • Overcome reluctance of users to change • Typical career path • Programmer • Programmer / Analyst • Systems Analyst

  8. Systems AnalystFunctions Coordination • Schedules and system-related tasks • Personnel • Manager • Programmers • Users • Vendors of computer equipment • Contractors

  9. Systems AnalystFunctions Communication • Oral presentations • Written documentation Planning and design • Plans and designs new system • Involved from beginning of project through final implementation of the system

  10. Systems AnalystPersonal Qualities • Analytical mind • Good communication skills • Self-discipline • Self-direction • Organizational skills • Creativity • Ability to work without tangible results

  11. SDLCSystems Development Life Cycle • Preliminary investigation • Analysis • Design • Development • Implementation

  12. SDLCPreliminary Investigation • Feasibility study / System survey • Determine the problem • Describe the problem • Understand management decisions • Organizational chart • Informal hierarchy • Produces rough plan and what to do

  13. SDLCPreliminary Investigation Problem Definition • Nature of the problem Separate problem from symptoms of problem • Scope of the project Budget and schedule • Objectives of the project What user thinks system should do

  14. SDLCPreliminary Investigation Report What you have found Recommendations Financially feasible

  15. SDLCPreliminary Investigation Resulting Management Decision • Drop • Fix a simple problem • Authorize the analysis phase

  16. SDLCAnalysis • Understand the existing system • Gather data • Analyze data • Establish system requirements

  17. SDLCAnalysis – Data Gathering • Written documents • Interviews • Structured • Unstructured • Questionnaires • Observation • Visits by appointment • Participant observation • Sampling

  18. SDLCAnalysis – Analyze Data • How the current system works • Determine system requirements • Basis for documentation • Tools • Data flow diagram (DFD) • Decision tables

  19. SDLCAnalysis – Data Flow Diagram

  20. SDLCAnalysis –Decision Tables

  21. SDLCAnalysis – System Requirements • Detailed list of things the system must be able to do • Design is based upon system requirements • Agreement upon requirements is needed before proceeding

  22. SDLCAnalysis – Report to Management • Summarize problems • Describe requirements • Cost analysis • Recommendations for next step • Obtain authorization to proceed

  23. SDLCDesign • Planning the new system • Two phases • Preliminary design • Detail design

  24. SDLCPreliminary Design Major system aspects • Centralized or distributed • Online or batch • PC-based? • How will input be captured? • Necessary reports

  25. SDLCPreliminary Design • Make or buy decision • Packaged software • Meet at least 75% of requirements? • Change business procedures for part or all of remainder? • Customize for part of all of remainder? • Custom software • Programmers write code • Outsourcing • System is developed by external organization

  26. SDLCPreliminary Design • Create an overall plan • Offer alternatives that meet requirements • Explain differences • Evaluate costs

  27. SDLCPreliminary Design • Build a prototype • Limited working system of subset • Does not need true functionality • Output looks like anticipated system output • Working model that can be modified and fine-tuned • Uses high-level software tools – CASE • Best for small-scale systems

  28. SDLCPreliminary Design CASE tools Computer-Aided Software Engineering • Supports specific analysis and design tasks • Integrated environment that supports the entire systems development process

  29. SDLCPreliminary Design Presentation • All alternatives • Selected plan • Prototype of the system • Obtain authorization to proceed

  30. SDLCDetail Design Parts of detail design phase • Output requirements • Input requirements • Files and databases • Systems processing • Systems controls and backup

  31. SDLCDetail Design Output requirements • Medium • Type of reports • Contents

  32. SDLCDetail Design

  33. SDLCDetail Design Input requirements • Medium • Content • Input forms • Validation • Volume

  34. SDLCDetail Design Files and Databases • Organization • Access • Format of records • Coordinate with database administrator regarding external databases and updating

  35. SDLCDetail Design Flowchart Symbols

  36. SDLCDetail Design

  37. SDLCDetail Design Systems Controls and Backup • Insure that input is processed correctly • Prevent fraud and tampering • System journals • Backup of system files

  38. SDLCDetail Design Report to Management • Detailed design specifications report • Presentation • Obtain authorization to proceed

  39. SDLCDevelopment • Doing the work to bring the new system into being • Scheduling

  40. SDLCDevelopment • Programming • Refine the design • Detailed logic flowcharts and pseudocode • Testing • Unit testing • System testing • Volume testing

  41. SDLCImplementation • Converting to the new system • Training • Equipment conversion • File conversion • System conversion • Auditing • Evaluation • Maintenance

  42. SDLCImplementation – Training • Begin during testing • User’s manual (Technical Writers) • Hands-on • Training consideration • Space • Equipment • Data • User’s schedules

  43. SDLCImplementation – Conversion • Equipment • Planning • Installation of new equipment • File • Manual to electronic • Special programs to convert old format to new

  44. SDLCImplementation – Conversion • System • Direct conversion • Phased conversion • Pilot conversion • Parallel conversion

  45. SDLCImplementation –Auditing • Audit trail • Trace output back to source

  46. SDLCImplementation – Evaluation • Working • Meets original requirements • Benefits • Meets budget • Improvements

  47. SDLCImplementation – Maintenance Ongoing activity for life of system

  48. Thank you

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