生产与运作管理03_ppt

3 Forecasting 3 2 LearningObjectives Listtheelementsofagoodforecast Outlinethestepsintheforecastingprocess Listsomemethodsofforecastingtechniques Identifythemajorfactorstoconsiderwhenchoosingaforecastingtechnique 3 3 FORECAST Astatementaboutthefuturevalueofavariableofinterestsuchasdemand Forecastingisusedtomakeinformeddecisions Long rangeShort range 3 4 Forecasts ForecastsaffectdecisionsandactivitiesthroughoutanorganizationAccounting financeHumanresourcesMarketingMISOperationsProduct servicedesign 3 5 UsesofForecasts 3 6 Assumescausalsystempast futureForecastsrarelyperfectbecauseofrandomnessForecastsmoreaccurateforgroupsvs individuals cancelingeffect Forecastaccuracydecreasesastimehorizonincreases FeaturesofForecasts 3 7 ElementsofaGoodForecast 3 8 StepsintheForecastingProcess 3 9 TypesofForecasts Judgmental usessubjectiveinputsTimeseries useshistoricaldataassumingthefuturewillbelikethepastAssociativemodels usesexplanatoryvariablestopredictthefuture 3 10 JudgmentalForecasts ExecutiveopinionsSalesforceopinionsConsumersurveysOutsideopinionDelphimethodOpinionsofmanagersandstaffAchievesaconsensusforecast 3 11 TimeSeriesForecasts Trend long termmovementindataSeasonality short termregularvariationsindataCycle wavelikevariationsofmorethanoneyear sdurationIrregularvariations causedbyunusualcircumstancesRandomvariations causedbychance 3 12 ForecastVariations Trend Irregularvariation Seasonalvariations 90 89 88 Figure3 1 Cycles 3 13 AssociativeForecasting Predictorvariables usedtopredictvaluesofvariableinterestRegression techniqueforfittingalinetoasetofpointsLeastsquaresline minimizessumofsquareddeviationsaroundtheline 3 14 ChoosingaForecastingTechnique NosingletechniqueworksineverysituationTwomostimportantfactorsCostAccuracyOtherfactorsincludetheavailabilityof HistoricaldataComputersTimeneededtogatherandanalyzethedataForecasthorizon 3 15 OperationsStrategy ForecastsarethebasisformanydecisionsWorktoimproveshort termforecastsAccurateshort termforecastsimproveProf