systems analysis and design chp 12

Systems design

A new or alternative information system is designed and a design report created.

systems analysis and design

a six-phase problem-solving procedure for examining and improving an information system. The six phases make up the systems life cycle.

preliminary investigation

First phase of the systems life cycle. It involves defining the problem, suggesting alternative systems, and preparing a short report.

Preparing a short report

For large projects, the systems analyst writes a report summarizing the results of the preliminary investigation and suggesting alternative systems. The report also may include schedules for further development of the project.

Suggesting alternative systems

This step is simply to suggest some possible plans as alternatives to the present arrangement.

parallel approach

old and new systems are operated side by side until the new one proves to be reliable.

Two alternative approaches that require much less time are

prototyping and rapid applications development.

Top-down analysis method:

used to identify the top-level components of a complex system. Each component is then broken down into smaller and smaller components. This approach makes each component easier to analyze and deal with.

Technical feasibility

Are reliable hardware, software, and training available to make the system work? If not, can they be obtained?

systems analysis report

describes the current information system, the requirements for a new system, and a possible development schedule.

Systems designers evaluate each alternative system for

feasibility

When choosing the best design, managers must consider these four questions:

(1) Will the system work with the organization's overall information system? (2) Will the system be flexible enough so it can be modified in the future? (3) Can it be made secure against unauthorized use? (4) Are the benefits worth the costs?

Acquiring hardware

Some new systems may not require new computer equipment, but others will. The equipment needed and the places where they are to be installed must be determined.

Preliminary investigation

The organization's problems or needs are identified and summarized in a short report.

Systems implementation

The new information system is installed, and people are trained to use it.

Systems analysis

The present system is studied in depth. New requirements are specified and documented.

systems analysis

This second phase of the systems life cycle determines the requirements for a new system. Data is collected about the present system and analyzed, and new requirements are determined.

systems analyst

design new systems or reorganize a company's computer resources to best utilize them. Analysts follow the systems life cycle through all its steps: preliminary investigation, analysis, design, development, implementation, and maintenance.

There are four approaches to conversion

direct, parallel, pilot, and phased.

Defining the problem

examining whatever current information system is in use. Determining what information is needed, by whom, when, and why is accomplished by interviewing and making observations.

Rapid applications development (RAD)

involves the use of powerful development software, small specialized teams, and highly trained personnel.

prototyping

means to build a model or prototype that can be modified before the actual system is installed.

direct approach

the conversion is done simply by abandoning the old and starting up the new. This can be risky. If anything is still wrong with the new system, the old system is no longer available to fall back on.

analyzing the data

the idea is to learn how information currently flows and to pinpoint why it isn't flowing appropriately. The whole point of this step is to apply logic to the existing arrangement to see how workable it is.

phased approach

the new system is implemented gradually over a period of time. The entire implementation process is broken down into parts or phases.

pilot approach

the new system is tried out in only one part of the organization. Once the system is working smoothly in that part, it is implemented throughout the rest of the organization.

systems audit

the system's performance is compared to the original design specifications. This is to determine whether the new procedures are actually furthering productivity. If they are not, some redesign may be necessary.

gathering data

the systems analyst—or the end user doing systems analysis—expands on the data gathered during Phase 1. He or she adds details about how the current system works.

some of the most popular tools made to assist systems analysts are....

the top-down analysis method, grid charts, system flow charts, data flow diagrams, and automated design tools.

systems development

three steps: (1) acquiring software, (2) acquiring hardware, and (3) testing the new system.

systems implementation

AKA Conversion; the process of changing—converting—from the old system to the new one and training people to use the new system.

computer-aided software engineering (CASE) tools.

AKA automated design tools; relieve the systems analysts of many repetitive tasks, develop clear documentation, and, for larger projects, coordinate team member activities.

Testing the system

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.

Systems maintenance

In this ongoing phase, the system is periodically evaluated and updated as needed.

Systems development

New hardware and software are acquired, developed, and tested

systems maintenance

Phase six of the systems life cycle consisting of a systems audit and periodic evaluation.

Economic feasibility

Will the costs of the new system be justified by the benefits it promises? How long will it take for the new system to pay for itself?

economic feasibility

Will the costs of the new system be justified by the benefits it promises? How long will it take for the new system to pay for itself?

Acquiring software

Application software for the new information system can be obtained in two ways. It can be purchased as off-the-shelf packaged software and possibly modified, or it can be custom-designed.

technical feasibility

Are reliable hardware, software, and training available to make the system work? If not, can they be obtained?

Operational feasibility

Can the system actually be made to operate in the organization, or will people—employees, managers, clients—resist it?

operational feasibility

Can the system actually be made to operate in the organization, or will people—employees, managers, clients—resist it?

organization chart

Chart showing the levels of management and formal lines of authority in an organization.

systems design

It consists of three tasks: (1) designing alternative systems, (2) selecting the best system, and (3) writing a systems design report.

systems life cycle

The six phases of systems analysis and design are called the systems life cycle. The phases are preliminary investigation, systems analysis, systems design, systems development, systems implementation, and systems maintenance.

systems analysts

These people study an organization's systems to determine what actions to take and how to use computer technology to assist them.

systems design report

prepared for higher management and describes the alternative designs. It presents the costs versus the benefits and outlines the effect of alternative designs on the organization.

Data flow diagrams

show the data or information flow within an information system. The data is traced from its origin through processing, storage, and output.

system flowcharts

show the flow of input data to processing and finally to output, or distribution of information.

Grid charts

shows the relationship between input and output documents.

automated design tools

software packages that evaluate hardware and software alternatives according to requirements given by the systems analyst.