可疑值的取舍-Trade-offs for doubtfu

可疑值的取舍Trade-offsfordoubtfulvalues知識點

pointofknowledge01可疑值的概念Theconceptofdoubtfulvalue02可疑值檢驗方法Suspiciousvaluetestmethod一、可疑值的概念I(lǐng)I.Theconceptofdoubtfulvalue可疑值：在一組平行測定數(shù)據(jù)中，有時會有個別測定值偏離其他測定值較遠，該值稱為可疑值或離群值。Suspiciousvalue:Inasetofparallelmeasurementdata,sometimestherewillbeindividualmeasurementvaluedeviatesfromtheothermeasurementvaluefarther,thevalueiscalledsuspiciousvalueoroutliers.一、可疑值的概念Ⅱ.Theconceptofdoubtfulvalue過失造成：保留數(shù)據(jù)會嚴重影響分析結(jié)果準確度和精密度，應(yīng)剔除可疑值。Causedbynegligence:

Retaineddatacanseriouslyaffecttheaccuracyandprecisionofanalyticalresults,andsuspiciousvaluesshouldbe

excluded.隨機誤差造成：舍棄數(shù)據(jù)會造成數(shù)據(jù)的浪費，不能隨意舍棄，應(yīng)進行統(tǒng)計檢驗來取舍。Randomerrorsarecausedby:roundingoffdatawillresultinwasteddataandshouldnotbedonearbitrarily,statisticaltestsshouldbeperformedtoroundoff.對可疑值應(yīng)做出如下判斷：Thefollowingjudgmentsshouldbemadeaboutsuspectvalues:二、可疑值檢驗方法ⅡMethodologyofthedoubtfulvaluetestQ檢驗法QTestmethod可疑值的檢驗方法Testsfordoubtfulvalues

Grubbs檢驗法GrubbstestQ檢驗法QTestmethod①將測定值按遞增順序排列①Arrangethemeasuredvaluesinincreasingorder.②計算測定值的極差（即最大值與最小值之差）②Calculatetheextremedeviationofthemeasuredvalue(i.e.,thedifferencebetweenthemaximumandminimumvalues)③計算可疑值與其相鄰值之差③

Calculatethedifferencebetweenthesuspectedvalueanditsneighboringvalues.④可疑值與最鄰近數(shù)據(jù)之差，除以極差，所得的商稱為Q計值④Thedifferencebetweenthesuspectvalueandthenearestneighboringdata,dividedbytheextremedeviation,andtheresultingquotientiscalledtheQ-metervalue二、可疑值檢驗方法Ⅱ.Methodologyofthedoubtfulvaluetest查Q值表，將Q計與Q表相比：ChecktheQ-valuetableandcomparetheQ-metertotheQ-table:二、可疑值檢驗方法Ⅱ.MethodologyofthedoubtfulvaluetestQ檢驗法QTestmethodQ計＞Q表

舍棄Q-meter>Q-meter

giveupQ計

≤Q表

保留Qmeter≤Qtable

Reserved3.59偏離其他數(shù)值較大，為可疑值，用Q檢驗法判斷有無可疑值需舍棄。3.59Alargedeviationfromothervaluesisasuspiciousvalue,andtheQ-testisusedtodetermineifthereisasuspiciousvaluetobediscarded.例題1Example1ⅠⅡⅢⅣⅤ測得值measuredvalue3.183.323.223.593.34二、可疑值檢驗方法Ⅱ.Methodologyofthedoubtfulvaluetest解：Solution:將測定數(shù)據(jù)按大小順序排列：3.18、3.22、3.32、3.34、3.59Putthemeasurementsinorderofmagnitude:3.18,3.22,3.32,3.34,3.59例題解析exampleanalysis判斷可疑值出現(xiàn)的位置：可疑值出現(xiàn)在末項Determinationofthelocationofthesuspiciousvalue:thesuspiciousvalueappearsattheendoftheitem二、可疑值檢驗方法Ⅱ.Methodologyofthedoubtfulvaluetest

二、可疑值檢驗方法Ⅱ.Methodologyofthedoubtfulvaluetest例題解析exampleanalysis測定次數(shù)Numberofmeasurements345678910Q0.900.940.750.640.560.510.470.440.41舍棄可疑數(shù)據(jù)的Q值表（置信度為90%）TableofQ-valuesfordroppingsuspectdata(witha90%confidencelevel)Q計（0.61）＜

Q表

（0.64）

保留Qmeter(0.61)<Qtable(0.64)

Reserved二、可疑值檢驗方法Ⅱ.Methodologyofthedoubtfulvaluetest

三、可疑值的取舍Ⅲ.Trade-offsbetweendoubtfulvalues用EDTA滴定某試劑中的Zn，消耗EDTA體積（mL）分別為：26.32，26.40，26.44，26.42，問26.32這個數(shù)據(jù)是否應(yīng)保留？ThevolumeofEDTAconsumed(mL)fortitrationofZninareagentwithEDTAis26.32,26.40,26.44,and26.42,andaskwhetherthefigureof26.32shouldberetained?例子examples三、可疑值的取舍Ⅲ.Trade-offsbetweendoubtfulvalues例子examples

可疑值與平均值的絕對差值為：Theabsolutedifferencebetweenthesuspectvalueandthemeanvalueis:

故26.32這一數(shù)據(jù)應(yīng)舍棄Therefore,thefigureof26.32shouldbediscarded科學態(tài)度scientificattitude數(shù)據(jù)處理要尊重科學規(guī)律Dataprocessingshouldrespectthelawsofscience環(huán)境監(jiān)測environmentalmonitoring食品安全檢測FoodSafetyTesting食品安全問題Foodsafetyissues用科學的態(tài)度和方法來處理數(shù)據(jù)Scientificapproachandmethodologytodata食品安全問題Foodsafetyissues用科學的態(tài)度和方法來處理數(shù)據(jù)ScientificapproachandmethodologytodataCaseReviewInSeptember2020,theMarketSupervisionAdministrationofGlossyCountyfoundthatChenMouhadover-addedalumduringtheproductionofsweetdoughnutsinthesamplingofsweetandsaltydoughnutsproducedandsoldbyChenJi,andthealuminumresidueinthedoughnutswas737mg/kg,whichwasseriouslyexceedingthenationalstandardlimit(≤100mg/kg).NanpingMunicipalMarketSupervisionBureauissuedthe“foodsafetyhazardsidentifiedexpertopinion”thatthesamplingsamples,aluminumresidueissufficienttocauseseriousfoodpoisoningorothersevereelectricalsourceofdisease.CasestatementThecourtheldthatChenMouviolatedfoodsafetystandards,intheprocessoffoodproductionandsales,overthelimitoftheabuseoffoodadditives,enoughtocauseseriousfoodpoisoningorotherseriousfood-borneillnesses,andhisbehaviorconstitutesthecrimeofproductionandsaleoffoodthatdoesnotmeetthesafetystandards,andthecrimeofproductionandsaleoffoodthatdoesnotmeetthesafetystandards,andthecrimeofproductionandsaleoffoodthatdoesnotmeetthesafetystandards.PopularKnowledgeAlumisatraditionalfoodimproverandbulkingagent,however,itschemicalcompositionispotassiumaluminumsulfate,containingaluminumions,exce