System Analysis and Design Flashcards
A collection of activities and elements organized to accomplish goal
System
Reasons to change information systems
◼ Organizational growth
◼ Mergers and acquisitions
◼ New marketing opportunities
◼ Revisions in governmental regulations
◼ Availability of new technology
A six-phase problem-solving procedure for examining and improving information
systems
System analysis and design
System’s Life Cycle
- Preliminary investigation
- Systems analysis
- Systems design
- Systems development
- Systems implementation
- Systems maintenance
the information problems or needs are identified
Preliminary Investigation
The present system is studied in depth. New requirements
are specified.
System Analysis
A new or alternative information system is designed
Systems design
New hardware and software are acquired, developed and
tested
Systems development
The new information system is installed and adapted to the
new system, and people are trained to use it
Systems implementation
In this ongoing phase, the system is periodically evaluated
and updated as needed
Systems Maintenance
Computer professionals studying an organization’s systems to determine what actions to take and how to use computer technology to assist them.
Systems Analysts
2nd top job classification after Computer Engineer (in terms of salary, prestige and security)
Computer Systems Analysts
Why it is important that end user understand how the systems life cycle works
▪ You may have to use the procedure
▪ More and more end users are developing their own information systems
▪ Will raise your computer competency
▪ Give you skills to solve wide range of problems
▪ Make you more valuable to an organization
◼ Determine the need for new information system
◼ Requested by an end user or a manager who
wants something done that is not presently
done
Phase 1 Preliminary Investigation
Three tasks Systems Analysts/End User is concerned with
- Briefly defining the problem
- Suggesting alternative solutions
- Preparing a short report
◼ examine whatever current information system is in use
◼ determine what information is needed, by whom, when, and why is accomplished by
interviewing and making observations
▪ Large information systems => Survey is done by a systems analysts
▪ Small information systems => Survey can be done by the end user
Defining the problem
Suggest some possible plans as alternatives to the present arrangement
Suggesting alternative solutions
The systems analyst writes a report summarizing the results of the preliminary investigation and suggesting alternative systems
▪ Report may include schedules for further development of the project.
▪ This document is presented to higher management, along with a recommendation to continue or discontinue the project
▪ Management then decide whether to finance the second phase
Preparing a short report
Problem -> Alternative -> Report -> Analysis
Phase 1 Preliminary Investigation
◼ Data is collected about the present system
▪ This data is then analyzed, and new requirements are determined
▪ Not concerned with a new design
▪ Only with determining the requirements for a new system
◼ Concerned with gathering then analyzing the data
◼ Completed by documenting the analysis in a report
Phase 2 Systems Analysis
Gather -> Analyze -> Report -> Design
Phase 2 systems analysis
◼ The systems analyst/end user doing systems analysis-expands on the data gathered during Phase 1
▪ Add details about how the current system works
◼ Data is/may be obtained
▪ Observations and interviews
▪ From questionnaires given to people using the system
▪ Studying documents that describe the formal lines of authority and standard operating procedures
Gathering Data
◼ Shows levels of management and formal lines of authority
◼ Resembles the hierarchy of three levels of management
▪ Top managers
▪ Middle managers
▪ supervisors
Organizational Chart
◼ The idea is to learn how information currently flows and to pinpoint why it isn’t flowing appropriately
◼ Apply logic to existing arrangement to see how workable it is
Analyzing the data
Analysis tools
◼ Checklists
◼ Top-down Analysis Method
◼ Grid Charts
◼ Decision Tables
◼ Systems Flowcharts
◼ Data Flow Diagrams
◼ Automated Design Tools
◼ A list of questions
◼ Helpful in guiding the systems analyst/end user through key issues for the present system
Checklist
◼ Identify the top-level components of a complex system
◼ Each component is then broken down into smaller and smaller components
▪ Makes each component easier to analyze and deal with
Top-down Analysis Method
◼ Shows the relationship between input and output documents
Grid charts
◼ Show the decision rules that apply when certain conditions occur
Decision Tables
◼ Show the flow of input data to processing and finally to output, or distribution of information
System flowcharts
◼ Show the data or information flow within the system
◼ The data is traced from its origin through processing, storage and output
Data Flow diagram
◼ Software packages that evaluate the hardware and software alternatives according to requirements given by the systems analyst
◼ also called Computer-Aided Software Engineering (CASE) tools
◼ These tools are not limited to system analysis
▪ Used in system design and development as well
◼ Relieve the systems analysts of many repetitive tasks
◼ Develop clear documentation,
◼ Coordinate team member activities (for larger projects)
Automated Design Tools
◼ Systems analysis report describes
- the current information system
- the requirements for a new system
- a possible development schedule
Documenting Systems Analysis
Consist of 3 tasks
◼ Designing alternative systems
◼ Selecting the best system
◼ Writing a systems design report
Phase 3: Systems Design
Feasibility
◼ Economic feasibility
◼ Technical feasibility
◼ Operational feasibility
Designing Alternative Systems
◼ Will the cost of the new system by the benefits it promises
◼ How long will it take for the new system to pay for itself
Economic feasibility
◼ Are reliable hardware, software, and training available to make the system work?
◼ If not, can they be obtained?
Technical feasibility
◼ Can the system actually be made to operate in the organization, or will people – employees, managers, clients – resist it?
Operational Feasibility
Managers must consider these four questions
◼ Will the system fit in with the organization’s overall information system?
◼ Will the system be flexible enough so it can be modified in the future?
◼ Can it be made secure against unauthorized use?
◼ Are the benefits worth the costs?
Selecting the best system
◼ Is prepared for higher management and describes the alternative designs
◼ Presents the costs versus the benefits and outlines the effect of alternative designs on the organization
◼ Usually concludes by recommending one of the alternatives
Writing a systems design report
3 steps
◼ Acquiring software
◼ Acquiring hardware
◼ Testing the new system
Phase 4: Systems Development
2 ways to obtain application software
◼ Purchased as off-the-shelf software and possibly modified
◼ Custom designed
Acquiring Software
◼ The equipment needed and the places where they are to be installed must be determined
▪ a very critical area
◼ Switching or upgrading equipment can be tremendously expensive proposition
▪ Will a computer system be sufficient as a company grows?
▪ Are networks expandable?
▪ Will people have to undergo costly training?
Acquiring hardware
◼ After the software and equipment have been installed, the system should be tested.
◼ Sample data is fed into the system.
◼ The processed information is then evaluated to see whether results are correct.
◼ Testing may take several months if the new system is complex.
Testing the new system
Another name for Phase 5
Conversion
◼ Direct Approach
◼ Parallel Approach
◼ Pilot Approach
◼ Phased Approach
Types of Conversion
Types of Conversion
◼ Direct Approach
◼ Parallel Approach
◼ Pilot Approach
◼ Phased Approach
- Abandon the old
- Very risky; not recommended
Direct Approach
- Run old and new side by side
- Very low risk; however, very expensive; not generally recommended
Parallel Approach
- Convert part of organization first
- Less expensive but riskier than parallel conversion; recommended for situations that many people performing similar operations
Pilot Approach
- Implement gradually
- Less risky but more expensive than parallel conversion; Recommended for situations with many people performing different operations
Phased Approach
◼ Training people is important
◼ One of the most commonly overlooked activities
Training
◼ Very important, ongoing activity
◼ Most organization spend more time and money on this phase than on any of the others.
Phase 6: Systems Maintenance
2 parts of systems maintenance
◼ Systems Audit
◼ Periodic Evaluation
◼ The system’s performance is compared to the original design specifications
▪ To determine whether the new procedures are actually furthering productivity
▪ If they are not, some redesign may be necessary
Systems Audit
◼ After the systems audit, the new information system is further modified, if necessary.
◼ All systems should be evaluated from time to time
▪ to determine whether they are
▪ meeting the goals
▪ providing the service they are supposed to
Systems Evaluation
Alternative Approaches that require much less time
◼ Prototyping
◼ Rapid Applications Development
◼ Means building a model or prototype that can be modified before the actual system is installed
◼ Users would try it out and provide feedback to the systems analyst
◼ The systems analyst would revise the prototype until the users felt it was ready to put into place.
Prototyping
◼ Involves the use of powerful development software, small specialized teams, and highly trained personnel.
Rapid Applications Development
