1. Copyright © 2003 by Prentice Hall Computers: Tools for an Information Age Chapter 14 Systems Analysis and Design: The Big Picture

2. 2Copyright © 2003 by Prentice Hall 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

3. 3Copyright © 2003 by Prentice Hall Objectives 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

4. 4Copyright © 2003 by Prentice Hall Computer Systems System – an organized set of related components established to accomplish a certain task Computer system – a system that has a computer as one of its components Computer system – a system that has a computer as one of its components

5. 5Copyright © 2003 by Prentice Hall Systems Analysis Studying an existing system to determine how it works and how it meets users’ needs Typically happens as a result of some impetus for change, combined with the authority to make the change Typically happens as a result of some impetus for change, combined with the authority to make the change

6. 6Copyright © 2003 by Prentice Hall Systems Design The process of developing a plan for an improved system, based on the result of the systems analysis

7. 7Copyright © 2003 by Prentice Hall Individuals Involved in Systems Analysis Systems analyst – performs analysis and design May perform some programming as well May perform some programming as well Client – the person or organization contracting to have the work done User – the people who will have contact with the system

8. 8Copyright © 2003 by Prentice Hall A Change Agent The catalyst or persuader who overcomes the reluctance to change within an organization Systems analyst can function as change agent, but it works best if it is someone inside the organization The common term for this is user involvement The common term for this is user involvement

9. 9Copyright © 2003 by Prentice Hall What It Takes to Be a Systems Analyst Coordination of many people, tasks, and schedules Communication, both oral and written Planning and design Specific personal qualities Specific personal qualities

10. 10Copyright © 2003 by Prentice Hall Personal Qualities An analytical mind Good communication skills Self-discipline and self-direction Good organizational skills Creativity The ability to work without tangible results Return

11. 11Copyright © 2003 by Prentice Hall The Systems Development Life Cycle Preliminary investigation Preliminary investigation Analysis Design Development Implementation

12. 12Copyright © 2003 by Prentice Hall Preliminary Investigation A brief study of the problem to determine whether the project should be pursued Also called the feasibility study or system survey Also called the feasibility study or system survey Defines the problem Defines the problem Defines the problem Defines the problem Also involves working with the users Organization chart – a hierarchical drawing showing the organization’s management Organization chart – a hierarchical drawing showing the organization’s management Organization chart Organization chart Return

13. 13Copyright © 2003 by Prentice Hall Defining the Problem Two points that must be agreed upon The nature of the problem The nature of the problem The scope (boundaries) of the problem The scope (boundaries) of the problem Agreeing on the problem helps define the objectives of the system Return

14. 14Copyright © 2003 by Prentice Hall An Organization Chart Return

15. 15Copyright © 2003 by Prentice Hall Analysis Understand the existing system Two tasks are involved Data gathering Data gathering Data gathering Data gathering Data analysis Data analysis Data analysis Data analysis Return

16. 16Copyright © 2003 by Prentice Hall Data Gathering A number of techniques can be used Written documents Written documents Interviews with users and managers Interviews with users and managers Structured interview – includes only questions that have been written out in advance Structured interview – includes only questions that have been written out in advance Unstructured interview – interviewer has a general goal but few, if any questions prepared Unstructured interview – interviewer has a general goal but few, if any questions prepared Questionnaires Questionnaires Observation Observation Sampling Sampling Return

17. 17Copyright © 2003 by Prentice Hall Data Analysis Two typical tools for data analysis Data flow diagram Data flow diagram Data flow diagram Data flow diagram Decision table Decision table Decision table Decision table Create system requirements Create system requirements Report to management Report to management Return

18. 18Copyright © 2003 by Prentice Hall Data Flow Diagram A map that graphically shows the flow of data through a system Used to diagram existing procedures and data flows Used to diagram existing procedures and data flows Return

19. 19Copyright © 2003 by Prentice Hall Decision Tables Show the table of logical decisions that must be made Useful in cases that involve a series of interrelated decisions Useful in cases that involve a series of interrelated decisions Help to ensure no alternatives are overlooked Help to ensure no alternatives are overlooked Return

20. 20Copyright © 2003 by Prentice Hall System Requirements A detailed list of things the system must be able to do The design of the new system will be based on these requirements The design of the new system will be based on these requirements Analyst and management must come to a clear agreement on requirements Analyst and management must come to a clear agreement on requirements Return

21. 21Copyright © 2003 by Prentice Hall Report to Management Summarizes the problems found in the current system Describes the requirements for the new system, including a cost analysis Makes a recommendation on what course to take next Return

22. 22Copyright © 2003 by Prentice Hall Design The new system is actually planned Divided into two subphases Preliminary design Preliminary design Preliminary design Preliminary design Detail design Detail design Detail design Detail design Return

23. 23Copyright © 2003 by Prentice Hall Preliminary Design Several key decisions must be made key decisions key decisions Build a prototype Build a prototype Return

24. 24Copyright © 2003 by Prentice Hall Key Decisions Write custom software or buy a software package (make or buy decision) Software packages may need to be customized Software packages may need to be customized Outsource software development or create in-house Develop alternatives (candidates) All candidates meet the client’s requirements but with variations in features and cost All candidates meet the client’s requirements but with variations in features and cost Return

25. 25Copyright © 2003 by Prentice Hall Prototyping Building a model of the system Typically a limited working system or subset of a system Typically a limited working system or subset of a system Developed very quickly Developed very quickly Designed to give the user an idea of what the system will look like Designed to give the user an idea of what the system will look like Computer-aided software engineering (CASE) tools Automate many of the tasks of the development process Automate many of the tasks of the development process Return

26. 26Copyright © 2003 by Prentice Hall Detail Design Develop detailed design specifications Output requirements Output requirements Output requirements Output requirements Input requirements Input requirements Input requirements Input requirements Files and databases Files and databases Files and databases Files and databases System processing System processing System processing System processing System controls and backups System controls and backups System controls and backups System controls and backups Return

27. 27Copyright © 2003 by Prentice Hall Output Requirements Things to consider The medium (paper, screen, etc.) of the output The medium (paper, screen, etc.) of the output The types of reports needed and what data is needed for the reports The types of reports needed and what data is needed for the reports Return

28. 28Copyright © 2003 by Prentice Hall Input Requirements Things to consider The input medium (captured at the source, keyed from source document) The input medium (captured at the source, keyed from source document) The fields needed, how they are laid out on the input screen, etc. The fields needed, how they are laid out on the input screen, etc. Input validation may be necessary Input validation may be necessary Return

29. 29Copyright © 2003 by Prentice Hall Files and Databases Things to consider How files are organized How files are organized Sequentially, directly, or by another method Sequentially, directly, or by another method The format of the records making up the data files The format of the records making up the data files Return

30. 30Copyright © 2003 by Prentice Hall System Processing Use a flowchart to show the flow of data through the system Return

31. 31Copyright © 2003 by Prentice Hall System Controls and Backup Controls are used to make sure data is input and processed correctly Also used to prevent fraud and tampering Also used to prevent fraud and tampering Types of controls differ depending on whether data is processed in a batch or online Types of controls differ depending on whether data is processed in a batch or online Transaction and master files should be backed up on a regular basis Copies should be stored in a safe location Copies should be stored in a safe location Return

32. 32Copyright © 2003 by Prentice Hall System Development Schedule and monitor the two principal activities Programming Programming Programming Testing Testing Testing There are several project scheduling tools available Return

33. 33Copyright © 2003 by Prentice Hall Programming Prepare program design specifications Use logic flowcharts and pseudocode to facilitate code development Return

34. 34Copyright © 2003 by Prentice Hall Testing Unit testing – verifies that individual program units work Perform testing with test data Perform testing with test data System testing – determines whether all program units work together as planned Volume testing – uses real data in large amounts Determines whether the system can handle a large volume of data Determines whether the system can handle a large volume of data Return

35. 35Copyright © 2003 by Prentice Hall Implementation Steps involved in starting the new system Training Training Training Equipment conversion Equipment conversion Equipment conversion Equipment conversion File conversion File conversion File conversion File conversion System conversion System conversion System conversion System conversion Auditing Auditing Auditing Evaluation Evaluation Evaluation Maintenance Maintenance Maintenance Return

36. 36Copyright © 2003 by Prentice Hall Training Teach users how to use the system The system will do no better than the people using it The system will do no better than the people using it Develop user’s manual to aid users who are not familiar with the system Develop user’s manual to aid users who are not familiar with the system Hands-on training is best Hands-on training is best Return

37. 37Copyright © 2003 by Prentice Hall Equipment Conversion Items to consider Delivery schedules must be coordinated Delivery schedules must be coordinated Terminals or personal computers must be networked Terminals or personal computers must be networked Devices on the system must be compatible Devices on the system must be compatible Return

38. 38Copyright © 2003 by Prentice Hall File Conversion If existing files are manual, they must be keyed in or scanned into the system Manual files must be kept current while data is being input into the new system Manual files must be kept current while data is being input into the new system If existing files are computer-based, programs must be written to convert the files into the format needed for the new system Return

39. 39Copyright © 2003 by Prentice Hall System Conversion Four approaches Direct conversion – the user simply stops using the old system and starts using the new one Direct conversion – the user simply stops using the old system and starts using the new one Phased conversion – the system is implemented one part at a time Phased conversion – the system is implemented one part at a time Pilot conversion – the entire system is used by a designated set of users Pilot conversion – the entire system is used by a designated set of users Parallel conversion – the old and new systems are both used until users are satisfied the new system works Parallel conversion – the old and new systems are both used until users are satisfied the new system works Return

40. 40Copyright © 2003 by Prentice Hall Auditing Systems to trace data in the system back to a source document Very helpful in tracing security violations Very helpful in tracing security violations Return

41. 41Copyright © 2003 by Prentice Hall Evaluation Determines how well the system is meeting the original requirements, benefits, and budgets Evaluation can be performed by the analyst and someone from the organization Evaluation can be performed by the analyst and someone from the organization Evaluation can also be performed by an independent third party Evaluation can also be performed by an independent third party Return

42. 42Copyright © 2003 by Prentice Hall Maintenance An ongoing activity that lasts the lifetime of the system Several types of maintenance activities Enhancements to the system Enhancements to the system Fix bugs in the system as they are identified Fix bugs in the system as they are identified Return