copyright © 1998 prentice hall 20001 systems analysis and design chapter 15 the big picture

Copyright © 1998 Prentice Hall 2000 1

Systems Analysis and Design

Chapter 15Chapter 15

The Big PictureThe Big Picture


Systems

A system is an organized set of A system is an organized set of related components established to related components established to accomplish a certain task.accomplish a certain task.

A computer system is a system that A computer system is a system that has a computer as one of its has a computer as one of its components.components.


Systems Analysis

Systems analysis is Systems analysis is the process of the process of studying an studying an existing system to existing system to determine how it determine how it works and how it works and how it meets client and meets client and user needs.user needs.


Clients and Users

ClientsClients contract to contract to have the systems have the systems analysisanalysis done. done.

UsersUsers are people who are people who will will havehave contact contact with the system with the system (employees and (employees and customers).customers).


Design

Systems Systems design is the design is the process of process of developing developing a plan for an a plan for an improved improved system.system.


Systems Analyst

The systems The systems analyst performs analyst performs both analysis both analysis and design.and design.

Sometimes a Sometimes a programmer is programmer is also involved in also involved in the analysis.the analysis.


Change

There must be an There must be an impetus for impetus for change and change and related authority related authority for change before for change before an analysis and an analysis and design project is design project is undertaken.undertaken.


Change Agent

The systems The systems analyst serves analyst serves as a catalyst to as a catalyst to overcomes the overcomes the natural natural reluctance to reluctance to change within change within an organization.an organization.


User Involvement

To overcome To overcome reluctance to reluctance to change, involve change, involve the people of the the people of the client client organization in organization in the development the development process.process.


Functions of theSystems Analyst

A systems analyst has three A systems analyst has three principal functions:principal functions:

• CoordinationCoordination• CommunicationCommunication• Planning and DesignPlanning and Design


Coordination

An analyst must An analyst must coordinate coordinate schedules and schedules and system-system-related tasks related tasks with a number with a number of people.of people.


Communication

The analyst may The analyst may need to make need to make oral presentations oral presentations and write reports and write reports for clients, users, for clients, users, and others and others involved with the involved with the system.system.


Planning and Design

The systems analyst, along with the The systems analyst, along with the client organization, plans and client organization, plans and designs the new system.designs the new system.

This includes all the activities from This includes all the activities from beginning of the project until its beginning of the project until its final implementation.final implementation.


Qualities of a Systems Analyst

Other desirable qualities of a Other desirable qualities of a systems analyst are:systems analyst are:

• analytical mindanalytical mind• self-disciplineself-discipline• self-directionself-direction• ability to work without tangible ability to work without tangible

resultsresults


Systems DevelopmentLife Cycle (SDLC)

The SDLC has five distinct phases:The SDLC has five distinct phases:

1. Preliminary investigation1. Preliminary investigation

2. Analysis2. Analysis

3. Design3. Design

4. Development4. Development

5. Implementation5. Implementation


1. Preliminary Investigation

The goal of this The goal of this phase is to phase is to determine the determine the problem and is problem and is sometimes called sometimes called the feasibility the feasibility study or system study or system survey.survey.


Tools of Preliminary Investigation

To determine To determine whether to whether to proceed with proceed with the project, the the project, the systems analyst systems analyst will develop an will develop an organizational organizational chart.chart.

Pres. C. Stenos

VP A.

Mapp

VP Z.

Hewn

Mark. I. Simon

Cust. O. Pine

Comp. V. Gear

Purch. R. South

Pay. J. Ria


Defining Problem

Defining the problem involves Defining the problem involves determining:determining:

• Nature of the problemNature of the problem• Scope of the problemScope of the problem• Objectives of the projectObjectives of the project


Nature of the Problem

The systems The systems analyst and the analyst and the users must users must agree on the agree on the nature of the nature of the problemproblem..


Scope of the Problem

Determining the Determining the scope of the scope of the problem sets problem sets limitations on limitations on the eventual the eventual budget and budget and schedules of the schedules of the project.project.


Objectives

Determining the Determining the objectivesobjectives means to means to express what express what the user thinks the user thinks the system the system should be able should be able to do.to do.


2. Systems Analysis

During this phase the systems During this phase the systems analyst must:analyst must:

• Gather dataGather data• Analyze dataAnalyze data• Determine system requirementsDetermine system requirements• Report to managementReport to management


Gathering Data

The systems analyst relies on the The systems analyst relies on the following sources when gathering data:following sources when gathering data:

• Written documentsWritten documents• InterviewsInterviews• QuestionnairesQuestionnaires• ObservationsObservations• SamplingSampling


Written Documents

Gathering documents Gathering documents includes procedures includes procedures manuals, forms, and manuals, forms, and any kind of material any kind of material that might have that might have bearing on the bearing on the problems in the problems in the organization.organization.


Interviews

There are two types of interviews, There are two types of interviews, structured and unstructured.structured and unstructured.

StructuredStructured interviews include only interviews include only preplanned questions.preplanned questions.

UnstructuredUnstructured interviews allow the interviews allow the systems analyst to digress from systems analyst to digress from the formal line of questioning.the formal line of questioning.


Questionnaires

Questionnaires are ideal for Questionnaires are ideal for gathering information from a group gathering information from a group too large to interview.too large to interview.


Observation

Systems analysts must Systems analysts must observe the flow of observe the flow of information in and out information in and out of an organization.of an organization.

Sometimes this requires Sometimes this requires them to be a them to be a temporary participant temporary participant in the organization.in the organization.


Sampling

Sampling is the Sampling is the collection of collection of data about data about quantities, costs, quantities, costs, time periods, time periods, and other factors and other factors relevant to the relevant to the system.system.


Analyze Data

The systems analyst uses charts and The systems analyst uses charts and diagrams to analyze the volume of diagrams to analyze the volume of data that has been collected.data that has been collected.

Techniques often used include:Techniques often used include:• Data flow diagramsData flow diagrams• Decision tablesDecision tables


Data Flow Diagrams (DFDs)

DFDs serve as a DFDs serve as a map of how data map of how data flows in and out of flows in and out of an organization an organization and reveal and reveal procedures used.procedures used.


Decision Tables

Unlike a data flow diagram, a Unlike a data flow diagram, a decision table represents the decision table represents the logical decisions that must be logical decisions that must be made regarding potential made regarding potential conditions in a given system.conditions in a given system.


System Requirements

The final segment of the systems The final segment of the systems analysis phase leads to a list of the analysis phase leads to a list of the things the system must be able to things the system must be able to do.do.

This list of system requirements will This list of system requirements will determine the design of the new determine the design of the new system.system.


Report to Management

• Problems identified in the current Problems identified in the current systemsystem

• Requirements for the new systemRequirements for the new system• Cost analysisCost analysis• Recommendations for future actionRecommendations for future action


3. Systems Design

This is the phase in which the This is the phase in which the systems analyst actually plans the systems analyst actually plans the new system.new system.

Systems design is divided into two Systems design is divided into two sub-phases:sub-phases:

• Preliminary designPreliminary design• Detail designDetail design


Preliminary Design

The systems analyst will review The systems analyst will review system requirements and consider system requirements and consider whether the system should be:whether the system should be:

• centralized or decentralizedcentralized or decentralized• networked or notnetworked or not• run with purchased or custom run with purchased or custom

softwaresoftware• outsourced or in-houseoutsourced or in-house


Prototyping

A prototype of the new system is a A prototype of the new system is a limited working system that is limited working system that is developed quickly to produce developed quickly to produce output that looks like the output output that looks like the output the finalized system will produce.the finalized system will produce.


Detail Design

The systems analyst must now develop The systems analyst must now develop detailed design specifications, such detailed design specifications, such as:as:

• Output requirementsOutput requirements• Input requirementsInput requirements• Files and databasesFiles and databases• Systems processingSystems processing• Systems controls and backupsSystems controls and backups


Output Requirements

The systems analyst must determine:The systems analyst must determine:• what the client wants the system to what the client wants the system to

produce.produce.• the medium of the output.the medium of the output.• the type of reports needed.the type of reports needed.• the contents of the output.the contents of the output.• what forms will be used.what forms will be used.


Input Requirements

The systems The systems analyst must analyst must determine what determine what input is required input is required to give the to give the desired output.desired output.


Files and Databases

The systems analyst will determine The systems analyst will determine whether the files should be stored whether the files should be stored sequentially, directly, or by some sequentially, directly, or by some other method.other method.

File storage must also be File storage must also be coordinated with the databases coordinated with the databases used by the client.used by the client.


Systems Processing

Systems Systems processing processing involves involves generating a generating a diagram of how diagram of how the flow of data the flow of data works in the works in the new system.new system.


Systems Controls and Backup

Systems controls are Systems controls are designed to prevent designed to prevent fraud and tampering.fraud and tampering.

In addition, system files In addition, system files should be backed up should be backed up (copied) and the copies (copied) and the copies stored in a safe manner stored in a safe manner and location.and location.


4. Systems Development

In this phase, the system is actually In this phase, the system is actually developed and includes:developed and includes:

• SchedulingScheduling• ProgrammingProgramming• TestingTesting


Scheduling

Scheduling deadlines and milestones Scheduling deadlines and milestones is another task of the systems is another task of the systems analyst.analyst.

Scheduling involves determining the Scheduling involves determining the allocation of people and resources, allocation of people and resources, monitoring schedules, and monitoring schedules, and producing status reports.producing status reports.


Programming

At this point in systems At this point in systems development, development, programmers are programmers are given program design given program design specifications and they specifications and they begin to write code.begin to write code.


Testing

After the After the program for program for the new the new system has system has been written, it been written, it must be tested must be tested under a variety under a variety of conditions.of conditions.


5. Implementation

For the implementation phase to be For the implementation phase to be successful, the following activities are successful, the following activities are required:required:

• TrainingTraining

• Equipment Equipment conversionconversion

• File conversionFile conversion

• System conversionSystem conversion

• AuditingAuditing

• EvaluationEvaluation

• MaintenanceMaintenance


Training

A system will A system will only be as only be as good as the good as the people who use people who use it. Therefore, it. Therefore, training the training the users is very users is very important.important.


Equipment Conversion

Implementing a system requires that Implementing a system requires that consideration has been given to consideration has been given to how best to convert to the new how best to convert to the new system.system.

Issues of availability of space, Issues of availability of space, accessibility, and cleanliness of the accessibility, and cleanliness of the work area cannot be overlooked.work area cannot be overlooked.


File Conversion

Converting old file structures to that Converting old file structures to that needed by the new system can needed by the new system can take a long time.take a long time.

Care must be taken to not corrupt Care must be taken to not corrupt old files, lose files, or disrupt old files, lose files, or disrupt normal operations of the client normal operations of the client organization during this organization during this conversion.conversion.


System Conversion

A systems analyst A systems analyst will need to will need to determine in what determine in what way the client way the client organization organization should convert to should convert to the old system.the old system.


Auditing

To guard against To guard against deliberate or deliberate or unintentional unintentional violations in violations in security, the security, the systems systems analyst designs analyst designs an audit trail.an audit trail.


Evaluation

Evaluation is needed to determine if Evaluation is needed to determine if the system is:the system is:

• workingworking• meeting the organizational meeting the organizational

requirementsrequirements• meeting the original budget meeting the original budget

limitationslimitations


Maintenance

Maintenance is an ongoing activity Maintenance is an ongoing activity and includes monitoring and and includes monitoring and making revisions throughout the making revisions throughout the life cycle of the system.life cycle of the system.


Conclusion

Each computer system is unique.Each computer system is unique.

A systems analyst must be able to A systems analyst must be able to identify and understand the unique identify and understand the unique characteristics of a client characteristics of a client organization to develop a better organization to develop a better system for them.system for them.