Theusefulnessofanymodeldependsinpartontheaccuracyandreliabilityofitsoutput.Yet,becauseallmodelsareimperfectabstractionsofreality,andbecausepreciseinputdataarerarelyifeveravailable,alloutputvaluesaresubjecttoimprecision.Inputdataerrorsandmodellinguncertaintiesarenotindependentofeach