Chapter 7 - Exercise answers

《Chapter 7 - Exercise answers》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Chapter7:DemandForecastinginaSupplyChainExerciseSolutions :Problem7-1:Weutilizeastaticmodelwithlevel,trend,andseasonalitycomponentstoevaluatetheforecastsforyear6.Initially,wedeseasonalizethedemandandutilizeregressioninestimatingthetrendandlevelcomponents.Wethenestimatetheseasonalfactors

2、foreachperiodandevaluateforecasts.EXCELWorksheet7-1providesthesolutiontothisproblem.Themodelutilizedforforecastingis:Thedeseasonalizedregressionmodelis:=5997.261+70.245tTheseasonalindicesforeachofthetwelvemonthsare:MonthS.IJAN0.427FEB0.475MAR0.463APR0.398MAY0.621JUN0.834JUL0.853AUG1.151

3、SEP1.733OCT1.778NOV2.124DEC1.095Forexample,theforecastforJanuaryofYear6isobtainedbythefollowingcalculation:F61=[5997.261+(61)*70.245]*0.4266=4386Thequalityoftheforecastingmethodisquitegoodgiventhattheforecasterrorsarenottoohigh.Problem7-2:Worksheet7-2comparesthefour-weekmovingaverageapp

4、roachwiththeexponentialsmoothingmodel(alpha=0.1).Inafour-weekmovingaveragemodeltheweightassignedtothemostrecentdatais0.25whereasinthecaseoftheexponentialsmoothingmodeltheweightassignedis0.1.Thefollowinggraphsdepicttheresultsfromthetwomodels.Forthisspecificproblem,itisevidentthatthemovin

5、gaveragemodelismoreresponsivethantheexponentialsmoothingapproachduethedifferenceinweightsallocation(0.25and0.1).UsingMADasameasureforforecastaccuracyitcanbeconcludedthatthemovingaveragemodel(MAD=9)isslightlymoreaccuratethantheexponentialsmoothingmodel(MAD=10)inevaluatingforecasts.Proble

6、m7-3:Thesimpleexponentialsmoothingmodelonlyconsidersthelevelcomponentanddoesnotincludeatrendcomponentintheanalysis.However,Holt’smodelallowsfortheincorporationofthetrendcomponentintotheanalysis.Worksheet7-3providestheresultsofthetwoapproaches.Byinvestigatingtherelationshipbetweensalesan

7、dperiod(shownintheabovegraph)itisevidentthatthedataexhibitsbothrandomfluctuationandtrend.Thus,itisnotsurprisingintheanalysisthatHolt’smodel(alpha=0.1,beta=0.1,MAD=8)isabetterapproachthanthesimpleexponentialsmoothingmodel(alpha=0.1,MAD=21).Problem7-4:Worksheet7-4evaluatesdemandf