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    Systems Analysis

    Transition to Systems Design

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    Systems Analysis and Design Fourth Edition

    Chapter 6

    Transition to Systems Design

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    Systems Analysis and Design Fourth Edition

    Objectives

    Evaluate software alternatives anddevelopment strategies

    Explain advantages and

    disadvantages of developing in-housesoftware versus purchasing and

    customizing a software package

    Describe how companies use out-sourcing and user applications

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    Systems Analysis and Design Fourth Edition

    Objectives

    List the steps in purchasing andevaluating a software package

    Explain the differences between a

    request for proposal (RFP) and arequest for quotation (RFQ)

    Describe the system requirements

    document and the presentation tomanagement at the end of the

    systems analysis phase

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    Systems Analysis and Design Fourth Edition

    Objectives

    Explain the transition from systemsanalysis to systems design, and the

    difference between logical and

    physical designExplain the importance of prototyping

    and describe various prototyping

    methods, tools, and techniques

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    Systems Analysis and Design Fourth Edition

    Objectives

    Discuss the systems design processand provide guidelines for system

    design

    Create and use appropriate codesduring systems design and

    development

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    Systems Analysis and Design Fourth Edition

    Chapter 6 covers the remaining tasksin the systems analysis phase

    Evaluation of alternative solutions

    Preparation of the system requirementsdocument

    Presentation to management

    Introduction

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    Systems Analysis and Design Fourth Edition

    Make or buy decisionIn-house software

    Developed by the companys IS department

    Software packagePurchased or leased from software publishers

    or vendors

    Horizontal application

    Vertical application

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Developing software in-houseReasons for in-house development

    Satisfy unique requirements

    Minimize changes in business procedures andpolicies

    Meet constraints of existing systems

    Meet constraints of existing technology

    Develop internal resources and capabilities

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Purchasing a software packageReasons for purchasing a software

    package

    Lower costs

    Less time to implement

    Proven reliability and performance

    benchmarks

    Less technical development staffFuture upgrades provided by the vendor

    Other companies as resources

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Customizing Software packagesPurchase a basic package that can be

    customized to suit your needs

    Negotiate with software vendor to makeenhancements to suit your needs

    Purchase the package and make your

    own modifications

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Other software alternativesApplication service providers (ASP)

    Outsourcing

    End-user applications

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Application service providersDelivers applications by charging a usage or

    subscription fee

    Service provided is called application hosting

    Offer applications on a rental basis

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    OutsourcingUsing outside companies to handle portion of

    the workload, on short-term or long-term basis

    Contract personnel firms

    Systems management or facilitiesmanagement firms

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    End-user systemsUtilizes standard business software

    Can offer simple, low-cost solutions

    Users can design their own data entry forms

    and reports

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Selecting a software alternativeDecision will affect remaining SDLC

    phases

    Systems analysts involvement dependson which alternative is selected

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Evaluating Software Alternatives

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    Systems Analysis and Design Fourth Edition

    Five step process1. Evaluate the information system

    requirements

    2. Identify potential software vendors3. Evaluate software package

    alternatives

    4. Make the purchase5. Install the software package

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    Step 1: evaluate the information systemrequirements

    Identify the key features of the system

    Estimate volume and future growthSpecify any hardware constraints

    Prepare a request for proposal or

    quotation

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    Step 2: identify potential softwarevendorsNext step is to contact potential vendorsAn RFP will help vendors to identify

    solutionsVarious sources of information on

    suppliersRetailersComputer manufacturersIndustry trade journals or Web sitesIT consultantsNewsgroups

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    Step 3: evaluate software packagealternatives

    Object is to compare software packages

    and select the best alternativeObtain information from many sources

    Evaluation process

    Obtain information from existing users

    Test the application

    Benchmark the package if necessary

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    Step 4: make the purchaseSoftware licenses

    Lease agreements

    Maintenance agreements

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    Step 5: install the software packageInstallation time depends on size and

    complexity

    Before using the package, complete allimplementation steps

    Loading, configuring, and testing the software

    Training users

    Converting data files to new format

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    Evaluation and selection teamsObjective of the process is to obtain the

    product with the lowest cost of ownership

    Team approach ensures that criticalfactors are not overlooked and that a

    sound choice is made

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    Evaluation and selection teamsPrimary objectives

    Eliminate system alternatives that will not

    work

    Rank the alternatives that will work

    Present the viable alternatives to management

    for a final decision

    Steps in Evaluating andPurchasing Software Packages

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    Systems Analysis and Design Fourth Edition

    System requirements documentAlso called software requirements

    specification

    Describes alternatives and makesrecommendation to management

    Similar to a contract for what will be

    delivered

    Must be clear and understandable to

    users

    Completion of Systems Analysis

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    Systems Analysis and Design Fourth Edition

    Presentation to managementFive probable management decisions

    1. Develop an in-house system

    2. Modify the current system3. Purchase or customize a

    software package

    4. Perform additional systemsanalysis work

    5. Stop all further work

    Completion of Systems Analysis

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    Systems Analysis and Design Fourth Edition

    Transition to Systems Design

    Essential to have an accurate andunderstandable system requirements

    document

    Errors, omissions, and ambiguities willaffect the quality of the finished

    product

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    Systems Analysis and Design Fourth Edition

    Transition to Systems Design

    Systems design overviewLogical design defines the functions and

    features of the system

    Also know as the essential model

    Physical design is a plan for the

    implementation of the system

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    Systems Analysis and Design Fourth Edition

    Transition to Systems Design

    The relationship between analysisand design

    Design phase cannot begin until analysis

    work is completeShould return to the analysis phase only

    in very limited situations

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    Systems Analysis and Design Fourth Edition

    Analysts must understand entirelogical design before beginningphysical design

    Systems design stepsReview the system requirements

    Design the systemOutput

    InputFiles and databases

    System architecture

    Present the systems design

    Overview of Systems Design

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    Systems Analysis and Design Fourth Edition

    Systems design objectivesBuild a system that is:EffectiveReliable

    Maintainable

    Overview of Systems Design

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    Systems Analysis and Design Fourth Edition

    Systems design considerationsUser considerationsMake the system user-friendly

    Consider where users receive output, or

    provide input to the systemAnticipate future needs

    Users

    Information system

    OrganizationMust provide flexibility

    Overview of Systems Design

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    Systems Analysis and Design Fourth Edition

    Overview of Systems Design

    Systems design considerationsData considerations

    Enter data where and when it occurs

    Verify data where it is input

    Use automated data-entry methods

    Control access for data entry

    Report all entries or changes to critical values

    Enter data into a system only onceAvoid data duplication

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    Systems Analysis and Design Fourth Edition

    Overview of Systems Design

    Systems design considerationsProcessing considerations

    Use a modular design

    Design modules that perform a single function

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    Systems Analysis and Design Fourth Edition

    Overview of Systems Design

    Design tradeoffsDesign goals often conflict with each

    other

    Easier use might create more complex

    programming requirements

    More flexibility might increase maintenance

    needed

    Meeting one users requirements might make

    it harder to satisfy anothers needs

    A major issue is quality versus cost

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    Systems Analysis and Design Fourth Edition

    Designing and Using Codes

    A code is a set of letters or numbersthat represents an item of data

    Overview of codes

    Codes serve many useful purposesSave storage space and costs

    Reduce data transmission time

    Decrease data entry time

    Can reveal or conceal information

    Can reduce input errors

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    Systems Analysis and Design Fourth Edition

    Designing and Using Codes

    Types of CodingSequence codes

    Block sequence codes

    Alphabetic codesCategory codesAbbreviation codesMnemonic codes

    Significant digit codes

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    Systems Analysis and Design Fourth Edition

    Designing and Using Codes

    Types of codingSequence codes

    Block sequence codes

    Alphabetic codesCategory codesAbbreviation codesMnemonic codes

    Significant digit codesDerivation codes

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    Systems Analysis and Design Fourth Edition

    Designing and Using Codes

    Types of codingSequence codesBlock sequence codes

    Alphabetic codes

    Category codesAbbreviation codesMnemonic codes

    Significant digit codesDerivation codesCipher codesAction codesSelf-checking codes

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    Systems Analysis and Design Fourth Edition

    Designing and Using Codes

    Developing a codeKeep codes conciseAllow for expansionKeep codes stable

    Makes codes uniqueUse sortable codesAvoid confusing codesMake codes meaningfulUse a code for a single purposeKeep codes consistent

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    EndChapter 6