accounting information systems.docx

accounting information systems.docx

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accountinginformationsystems

SOLUTIONSFOR

CHAPTER4

DiscussionQuestions

DQ4-1"Dataflowdiagramsandflowchartsprovideredundantpicturesofaninformationsystem.Wedon'tneedboth."Discuss.

ANS.Logicaldataflowdiagrams（DFDs）presentonlythelogicalelementsofaninformationsystem.Byexcludingthephysicalelements,thelogicalDFDallowsustoconcentrateonwhatasystemisdoingwithoutbeingdistractedbyhowthefunctionsarebeingperformedandbywhom.

PhysicalDFDspresentthephysicalelementsofaninformationsystem.Theyconcentrateonwhoisactingonthedataflowingthroughthesystem.PhysicalDFDsallowustoconcentrateontheentitiesinvolvedinprocessinginformation.Wecanalsoseehowmuch“work”isdonebyanentitybyobservingtheflowsintoandoutofanentityandwhetherthoseflowschangenames,anindicationthattheyhavebeentransformedwithintheentity.

Finally,aflowchartpresentsthelogicalandthephysicaldetailsofasystem'sfunctions.Itshowsthedetailsofhowaprocessisaccomplishedandalsoshowstheorganizationalunitthatperformstheprocess.AswewillseeinChapter9,thesedetailsarenecessarytopermitevaluationofasystem'scontrols.Also,systemsflowchartsdescribeexceptionanderrorroutines,whichDFDsdonot.DFDsconcentrateonusualandrecurringevents.

Inconclusion,itisonlywithallofthesediagramsthatwecangetacompletepictureofaprocess.Asnotedabove,however,eachdiagramhasitfunctionand,dependingonourpurpose,allmaynotbeneeded.

DQ4-2"Itiseasiertolearntopreparedataflowdiagrams,whichuseonlyafewsymbols,thanitistolearntoprepareflowcharts,whichuseanumberofdifferentsymbols."Discuss.

ANS.ComparetheDFDsymbolsinFigure4.1totheflowchartingsymbolsinFigure4.6andyouprobablyconcludethatitisquiteeasytolearntheDFDsymbols.Also,examineFigure4.7andseethatthereareseveralstandardroutinesusedinflowcharts.Also,webelievethatconstructingDFDspresentsfewerproblemsindetermininglayoutandplacementofsymbols.Weconclude,therefore,thatDFDsareeasiertoconstructthanareflowcharts.Youmighthaveadifferentopinion.

DQ4-3Describethewho,what,where,andhowofthefollowingscenario.Acustomergiveshispurchasetoasalesclerk,whoentersthesaleinacashregisterandputsthemoneyintheregisterdrawer.Attheendoftheday,thesalesclerkgivesthecashandtheregistertapetothecashier.

ANS.Who=Thesalesclerkperformsthedataprocessingactivities.Thecustomerandthecashierareentitiesintherelevantenvironment.

What=

（1）Givepurchasetosalesclerk

（2）Entersaleinregister（ifitisanelectronicregister,datastorescouldbeupdated）

（3）Putmoneyindrawer

（4）Givecashandregistertapetocashier.

Where=Store.

How=Amanualprocessisperformedbythesalesclerkusingacashregister.

DQ4-4WhyaretheremanycorrectlogicalDFDsolutions?

WhyisthereonlyonecorrectphysicalDFDsolution?

ANS.Foreachsensiblegroupingoflogicalactivities,thereisacorrectlogicalDFD.And,sincethereareoftenmanysensiblegroupings,therearemultiplecorrectsolutions.However,thereisonlyonecorrectphysicalDFDforeachsystem,becausethesediagramsareconstructeddirectlyfromadescriptionofthesystem.Thereisaone-to-0necorrespondencebetweenentitiesandbubbles,leavinglittleornoroomforinterpretation.

DQ4-5Explainwhyaflowfromahigher-toalower-numberedbubbleonalogicalDFDisaphysicalmanifestationofthesystem.Giveanexample.

ANS.IfwefeelthatwemustsendadataflowfromonebubbleonalogicalDFDtoabubbleonthatdiagramwithalowernumber,thenwemusthaveapictureinourmindofthatlower-numberedbubbleasaperson,place,orthingratherthanalogicalactivity.Ifyouhavesuchapicture,yourdiagramwillrepresentaphysicaldescriptionofthesystem,regardlessofthelabelsthatwemightassigntotheflowsandtothebubbles.Let'suseFigure4.11foranexample.IfinthatDFDwesentthedataflow"Cashreceiptstotal"tobubblenumber2.0,wewouldhaveaphysicaldataflow.Perhapsweincludedsuchaflowbecausewepicturebubble2.0asaplaceratherthanasafunction.ThatwouldbeamistakeinconstructingalogicalDFD.

DQ4-6CompareandcontrastthepurposeofandtechniquesusedindrawingphysicalDFDsandlogicalDFDs.

ANS.WedrawphysicalDFDstodepictasystem'sentities—bothinternalandexternal—andtocharacterizethecommunicationsbetweenthoseentities.WedrawlogicalDFDstodescribethefunctions—orinformationprocessingactivities—performedbythesystem.

WeusethesamesymbolsfordrawinglogicalandphysicalDFDs.However,thewayweusethosesymbolsdiffers.InaphysicalDFD,thebubblesarelabeledwiththenamesofentities,whileinalogicalDFD,thelabelsdescribethefunctionsbeingperformed.InaphysicalDFDthelabelsonthedataflowsandonthedatastoresareactualspecificnamesthatdescribethemethodusedforcommunicatingandforstoringthedata,whileinalogicalDFD,thoselabelsaregenericdescriptionsornamesthatdescribethedata.

DQ4-7"Ifwedocumentasystemwithasystemflowchartanddataflowdiagrams,wehaveover-documentedthesystem."Discuss.

ANS.Wedon'tagreewiththisstatement.Eachtooldocumentsadifferentaspectofasystemandisusedforadifferentpurpose

Asystemsflowchartdepictsasystem'sinformationandoperationsactivitiesandsuperimposesthoseactivitiesontotheorganization'sstructure.Weusetheflowcharttounderstandthesystem'sactivities—bothinformationandoperations—andtoanalyzethesystem'scontrols.

Dataflowdiagramsconcentrateonthedata,theentitiesthatactonthedata,andtheinformationsystemsfunctionsbeingperformedbyasystem.WeusetheDFDstoanalyzeeachoftheseelementsofasystem.Also,weusethelogicalDFDextensivelyinthedevelopmentofnewsystems.

DQ4-8"Preparingatableofentitiesandactivitiesasthefirststepindocumentingsystemsseemstobeunnecessaryandundulycumbersome.Itwouldbealoteasiertobypassthisstepandgetrighttothenecessarybusinessofactuallydrawingthediagrams."Doyouagree?

Discussfully.

ANS.Wedon'tagree.Withpractice,preparationofatableofentitiesandactivitiesisnotdifficult.Also,wefindthatweprefertopreparethistablebeforedrawinganydiagramsbecausethetablehelpsustolayoutthediagramsandtoavoidmistakesandminimizetheneedforredrawing.

DQ4-9"Intermsofthesequenceusedindocumentingsystems,itwouldbeeasiertoprepareasystemsflowchartbeforewepreparedataflowdiagrams."Doyouagree?

Discussfully.

ANS.Wedon'tagree.Thoseofyoufamiliarwithflowcharts—andnotfamiliarwithDFDs—mightprefertostartwithaflowchart.However,ourexperienceisthataflowchartisthemostdifficultofthediagramstodrawbecause:

theflowchartusesmanymoresymbolsthantheotherdiagrams,mustbecarefullylaidout,andmayrequirecomplicatedon-andoff-pageconnectors.AftercompletingthetableofentitiesandactivitiesandtheDFDs,wehavefoundthatcompletingasystemsflowchartisrelativelyuncomplicated.

DQ4-10"Sincetherearecomputer-baseddocumentationproductsthatcandrawdataflowdiagramsandsystemsflowcharts,learningtodrawthemmanuallyisawasteoftime."Doyouagree?

Discussfully.

ANS.Wedisagree,partly.Wehaveusedcomputer-baseddocumentationpackagesandbelievethatyoumustknowsomethingaboutdrawingDFDsandflowchartsbeforeyoucanusesuchpackageseffectively.However,youmightdevelopyourdocumentingskillsbyusingsuchapackageratherthanbypracticingmanualdiagrampreparation.ThefacultyinourEnglishdepartmentbelievesthatstudentscanbebetterwriters,iftheylearntowriteusingaword-processingpackage.PerhapsstudentswouldpreparebetterdocumentationiftheyweretolearntoprepareDFDsandflowchartswhileusingadocumentationpackage.

Problems

NOTETOINSTRUCTORS:

AdditionalproblemscanbecreatedfromthediagramsandsolutionsforProblems4-1through4-3.First,youcouldprovidethestudentswiththenarrativeandapartiallycompleteddiagramrequiringthatthestudentsfillinthemissingpartsofthediagram.Or,youcouldprovidethediagramandapartiallycompletednarrativeandrequirethatthestudentsfillintheblanksinthenarrative.

P4-1ANS.

AttheCompany’ssalesoffice,salesrepresentativesanswercustomercallsandentercustomerordersintothecomputer.ThecomputeraccessestheInventorymasterdata（ondisk）todeterminetheavailabilityandpricesfortheitemsrequested.Also,thecomputeraccessestheCustomermasterdata（ondisk）todeterminethecustomer’screditlimitandcomparesthatlimittothebalanceoutstandingontheAccountsreceivablemasterdata（ondisk）andtotheamountoftheorder.

Next,thecomputerupdatestheinventorymasterdataandnotifiestheclerkthattheorderhasbeenaccepted.Theclerknotifiesthecustomerbyphone.Also,thecomputerprintsatwo-partpickingticketonaprinterlocatedinthewarehouse.Inthewarehouse,clerksannotatethepickingticket（weassumethatitisannotatedwiththequantitiespicked）,filecopy2inthewarehouseandsendcopy1toshipping（weassumethatitissentalongwiththegoods）.

Inshipping,clerksprepareatwo-partpackingslip,filecopy2withtheannotatedpickingticketandgivecopy1tothecarrier（weassumethatthepackingslipisattachedtothegoods）.

P4-2ANS.

Potentialcustomerscontactthiscompanywitharequestforservices.AcontractispreparedandfiledintheContractfile