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Systems Analysis and Design:The Big Picture

Computers:Tools for an Information Age


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ObjectivesDefine the terms system, analysis, anddesign Describe the principal functions of thesystems analystList and describe the phases of the systemsdevelopment life cycleDescribe the various data-gathering andanalysis toolsDescribe a selection of systems design toolsExplain the concept of prototypingExplain the role of the maintenance task inthe systems development life cycle


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Systems Analysis DesignSystem an organized set of related componentsestablished to accomplish a certain task

Computer system a system that has a computer as one ofits components

Analysis - Studying an existing system to determinehow 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

Design - The process of developing a plan for animproved system, based on the result of the systemsanalysis


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Who Participates?

ProjectTeam


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Key Individuals Involved in

Systems AnalysisSystems analyst performs analysisand design

May perform some programming as wellClient the person or organizationcontracting to have the work done

User the people who will have contactwith the system


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Systems Analyst: A Change AgentThe catalyst or persuader who overcomes thereluctance to change within an organizationSystems analyst can function as change agent,but it works best if it is someone inside theorganizationWhat it takes:

Coordination of many people, tasks, and schedulesCommunication skills, both oral and written

Planning and design (an analytical mind)Self-discipline and self-directionGood organizational skillsCreativityThe ability to work without tangible results


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System Development Life

Cycle (SDLC)Organized set of activities that guidesthose involved through the development

of an information system.

PhasesPreliminary Investigation

Analysis

DesignDevelopment(Documentation)Implementation

Ongoing activitiesProject managementOverall

DocumentationInformation gathering


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System Development

GuidelinesUse a structured approach

Involve the Users

Develop Standards


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Ongoing Activity: Project Management

The process of planning, scheduling, and controlling

activities during the SDLCScope (goal, objectives, expectations)

Activities and Deliverables to be completed

Time estimatesCost estimatesOrder activities occur

Activities performed concurrently

Gantt Chart

Project Plan


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Ongoing Activity: Documentation

Compilation and summarization of dataand information

ReportsDiagramsProgramsOther deliverables generated during SDLC

Project NotebookProject Dictionary/Repository


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Ongoing Activity: Data & Info Gathering

Review currentsystem

documentationObserveSendQuestionnaires

InterviewStructured/Unstructured

Conduct JAD (jointapplication design)sessionsResearch

Begins in Analysis Phase, but is continually updated


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Phase 1: Preliminary Investigation

A brief study of the problem to determinewhether the project should be pursued

Also called the feasibility study or systemsurvey

Involves working with the users

Organization chart a hierarchical drawingshowing the organizations management


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Feasibility StudyTechnical feasibilityEconomic feasibilityOperational feasibility

are the current work practices and proceduresadequate to support the new system?Legal feasibility

Schedule feasibilityhow long will the system take to develop, or can itbe done in a desired time-frame?


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Defining the Problem

Two points that must beagreed upon

The nature of the problemThe scope (boundaries) ofthe problem

Agreeing on the problem

helps define theobjectives of the system


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ProjectRequest


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Feasibility Assessment


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Feasibility Assessment

(continued)


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Phase 2: Analysis

Understand the existing systemTwo tasks are involved

Data gatheringData analysis


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Data Analysis

Typical tools for data analysisEntity Relationship diagram

Data flow diagramDecision table/Decision TreeWritten report

Report to management/ customer/ client


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Entity-Relationship Diagrams(ERD)

Tool to graphically represent the associationsbetween entities in the project

Noun

Verb


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Data Flow Diagrams (DFD)Tool to graphically represent the

flow of data in a system

Data Store


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Decision

Table

DecisionTree


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System Requirements

& recommendations A detailed list of things the system must be able todo

Highlight problems with current systemThe design of the new system will be based on theserequirements

Analyst and management must come to a clear

agreement on requirementsList of possible solutionsHardware/software recommendations


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Report to Management

Summarizes the problems found in thecurrent system

Describes the requirements for the newsystem, including a cost analysisMakes a recommendation on whatcourse to take next


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Phase 3: DesignThe new system is actually plannedDivided into two subphases

Preliminary designSeveral key decisions must be made

Detail design specificationsOutput requirementsInput requirements

Files and databasesSystem processingSystem controls and backups


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Build or Buy?

Custom SoftwareDeveloped by user

Developed at userrequest by outsidevendor

Packaged SoftwareHorizontal

Many org types Vertical

Industry specific


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Acquire Hardware/Software

Technical specificationsSolicit vendor proposalsTest & evaluate

Benchmark Test

Make a decision


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Input OutputThings to consider

The medium (paper,screen, etc.) of theoutputThe types of reportsneeded and whatdata is needed forthe reports

Things to considerThe input medium(captured at the source,keyed from sourcedocument)The fields needed, howthey are laid out on theinput screen, etc.Input validation may benecessary

Requirements


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Input/Output Design

Mockup(User)

Layout Chart(Programmer)


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Files and Databases

Things to considerHow files are organized

Sequentially, directly, or by another methodThe format of the records making up thedata files


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Database Design

Table structure definitions & relationshipsSecurity

S P i


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Program Design

File

Hard copComment

Flow ChartSystem Processing


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Programming

Prepare program design specificationsUse logic flowcharts and pseudocode tofacilitate code development


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Testing

Unit testing verifies that individualprogram units work

Perform testing with test dataSystem testing determines whether allprogram units work together as plannedVolume testing uses real data in largeamounts

Determines whether the system canhandle a large volume of data


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Phase 5: Implementation

Steps involved in starting the new systemTrainingEquipment conversionFile conversionSystem conversion

Auditing

EvaluationMaintenance


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Training

Teach users how to use the systemThe system will do no better than the

people using itDevelop users manual to aid users whoare not familiar with the system

Hands-on training is best


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Equipment Conversion

Items to considerDelivery schedules must be

coordinatedTerminals or personal computersmust be networked

Devices on the system must becompatible


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File Conversion

If existing files are manual, they must bekeyed in or scanned into the system

Manual files must be kept current whiledata is being input into the new system

If existing files are computer-based,

programs must be written to convert thefiles into the format needed for the newsystem


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System Conversion

Four approachesDirect conversion the user simply stops usingthe old system and starts using the new onePhased conversion the system is implementedone part at a timePilot conversion the entire system is used by adesignated set of usersParallel conversion the old and new systems areboth used until users are satisfied the new systemworks


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Conversion Options


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Auditing

Systems to trace data in the systemback to a source document

Very helpful in tracing security violations


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Evaluation

Determines how well the system ismeeting the original requirements,

benefits, and budgetsEvaluation can be performed by theanalyst and someone from the organization

Evaluation can also be performed by anindependent third party


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Maintenance

An ongoing activity that lasts the lifetimeof the system

Several types of maintenance activitiesEnhancements to the systemFix bugs in the system as they are

identified


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Terms to Know: Chapter 14 AnalysisBenchmark testBuild-or-buy decisionCASECost/benefit analysisData dictionaryData flow diagramDecision tree/Decision tableDeliverableDesignDevelopmentDirect conversionDocumentationEntity-relationship diagram (ERD)Feasibility Assessment/StudyGantt chartJoint application development (JAD)Layout chartMockup

OutsourcingParallel conversionPhased conversionPilot conversionPost-implementation system reviewPreliminary investigationProject dictionary

Project planPrototypeRFP, RFQ, RFIScopeSystemSystem design

System development life cycle-SDLCSystem testingSystems analystUnit testingVolume testing


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If asked, can you Define the terms system, analysis, anddesign Describe the principal functions of thesystems analystList and describe the phases of the systemsdevelopment life cycleDescribe the various data-gathering andanalysis toolsDescribe a selection of systems design tools

Explain the concept of prototypingExplain the role of the maintenance task inthe systems development life cycle


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Sources

Capron; Computers: Tools for AnInformation Age, 8 th Ed. 2003

Pfaffenberger; Computers in YourFuture 2003Microsoft Clipart
http://office.microsoft.com/clipart/default.aspx?lc=en-ushttp://office.microsoft.com/clipart/default.aspx?lc=en-us

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