1. Systems Analysis and Design
Computing Essentials
Systems Analysis and Design

2. Computing Essentials 1999 - 2000
Overview
Effective information systems don’t happen by accident, they are the result of considerable thought and effort
A six step problem-solving process called systems analysis and design underpins the development of effective information systems
Computing Essentials
Systems Analysis and Design

3. System Analysis and Design
System - “collection of activities and elements organized to accomplish a goal”
Information system - “collection of hardware, software, people, procedures and data”
Computing Essentials
Systems Analysis and Design

4. The Traditional Systems Development Life Cycle (SDLC)
The SDLC is a structured framework that consists of sequential processes by which information systems are developed.
Computing Essentials

5. System Analysis and Design Steps
Preliminary investigation – overview of problems and solutions, feasibility considered, report prepared
Systems analysis - system studied, new requirements specified
Systems design - new or alternative system design to solve problem
Computing Essentials
Systems Analysis and Design

6. System Analysis and Design Steps
Systems development - new hardware and software acquired, developed and system tested (not live)
Systems implementation – conversion to new live system with training
Systems maintenance - periodic evaluation and updating
Computing Essentials
Systems Analysis and Design

7. Systems Analysis and Design
Computing Essentials
Systems Analysis and Design

8. Phase 1: Preliminary Investigation
In the preliminary investigation phase, the problems are briefly identified and a few solutions are suggested
Computing Essentials

9. Phase 1: Preliminary Investigation
To determine if a new system is needed, problems are briefly identified and a few solutions are suggested
Systems analysts here are concerned with three tasks:
Briefly defining the problem
Suggesting alternative solutions
Preparing a short report
Computing Essentials

10. Phase 1: Preliminary Investigation
Defining the problem
Examining current system
By observation and interview, determining what information is needed by whom, when, where and why
Suggesting alternative systems
Short report summarizing investigation results
Computing Essentials

11. Computing Essentials 1999 - 2000
Phase 1: Preliminary Investigation
Alternative systems are designed and evaluated for
Economic feasibility - do benefits justify costs?
Technical feasibility - is reliable technology and training available?
Operational feasibility - will the employees, managers or clients support it?
Time feasibility – can the project be competed within a suitable time frame?
Computing Essentials

12. Computing Essentials 1999 - 2000
Phase 2: Analysis
In the systems analysis phase, the present system is studied in depth, and new requirements are specified.
Computing Essentials

13. Computing Essentials 1999 - 2000
Gathering Data
Expanding on data gathered in Phase 1
In addition to observation and interviews, formal lines of authority and standard operating procedures investigated
Organization chart excellent source document during this phase
Computing Essentials

14. Organisation chart and management pyramid
CEO
VP Accounting
VP Marketing
VP Production VP HR
VP Research
… etc
Workers
Supervisors
Control
Middle Manager
Control & Planning
Top Managers
Long-Range Planning
Organisation chart and management pyramid
Computing Essentials

15. Computing Essentials 1999 - 2000
Analyzing the Data
How information flows, and reasons for any inefficiencies
Checklists - list of questions
Top-down analysis methodology - start with top level components, break down through each successive level
Computing Essentials

16. Computing Essentials 1999 - 2000
Analyzing the Data
Grid charts - to show relationship between inputs and outputs
System flowcharts - charts flow of input data to processing and finally to output
Data flow diagrams - displays data or information flow within an information system
Computing Essentials

17. Computing Essentials 1999 - 2000
System Flowchart
Computing Essentials

18. System Flowchart Symbols
decision
Computing Essentials

19. Computing Essentials 1999 - 2000
Analyzing the Data
Automated design tools
Help systems analyst evaluate hardware and software alternatives
Often called computer-aided software engineering tools or CASE tools
Computing Essentials

20. Computing Essentials 1999 - 2000
Client Database
Client Information
Update if necessary
Request Service
Client
Request Accepted
Completed Service
Time & Billing Database
Verify Account
Perform Service
Request Denied
Bill Mailed
Prepare Client Bill
Database Updated
Data Flow Diagram
Data Flow Diagram (DFD) Symbols
Computing Essentials
Data Flow
Entity
Process
File

21. Documenting the Systems Analysis Stage
In report to higher management
Current system described
Requirements for new system specified
Possible development schedule proposed
Computing Essentials

22. Computing Essentials 1999 - 2000
Phase 3: Design
Systems analysis describes what a system must do to solve the business problem, and systems design describes how the system will accomplish this task
Computing Essentials

23. Computing Essentials 1999 - 2000
Phase 3: Design
In selecting the best system, questions that must be answered:
Will new system fit into overall system?
Will it be flexible for the future?
Can it be secured against unauthorized use?
Are the costs worth the benefits?
Writing the systems design report - alternatives described, one recommended
Computing Essentials

24. Computing Essentials 1999 - 2000
The deliverable of the systems design phase is the technical design -- that specifies the following:
System outputs, inputs, and user interfaces
Hardware, software, databases, telecommunications, personnel, and procedures
How these components are integrated
Computing Essentials

25. Two Major Aspects of the New System
Logical systems design
States what the system will do
Physical systems design
States how the system will perform its functions
Computing Essentials

26. Computing Essentials 1999 - 2000
Phase 4: Development
In the systems development phase, new hardware and software are developed, acquired and tested.
Computing Essentials

27. Computing Essentials 1999 - 2000
Phase 4: Development
Developing software - two options
Off-the-shelf
Custom designed
Acquiring hardware - what kinds needed and where to install
Testing the new system
Sample data fed into system
Results evaluated
Computing Essentials

28. Phase 5: Implementation
In the systems implementation phase, the new information system is installed, and people are trained to use it.
Computing Essentials

29. Phase 5: Implementation
Types of conversion
Direct approach - old system abandoned, new one adopted
Parallel approach - both systems operated side by side until new system proves itself
Computing Essentials

30. Phase 5: Implementation
Types of conversion (cont.)
Pilot approach - new system launched in only one area of the business, once system operating smoothly implementation goes company-wide
Phased approach - gradual implementation over time
Computing Essentials

31. Phase 5: Implementation
Pilot and phased approach most favored
Training
Most commonly overlooked
Can be commenced before equipment delivery
Outside trainers sometimes used
Computing Essentials

32. Computing Essentials 1999 - 2000
Phase 6: Maintenance
Systems maintenance is first a systems audit and then an ongoing evaluation to see whether a system is performing productively.
Computing Essentials

33. Computing Essentials 1999 - 2000
Phase 6: Maintenance
Systems audit - performance compared to original specifications
Periodic evaluation - “checkups” from time to time, modifications if necessary
Computing Essentials