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MatlabTutorialCOM848M1ResearchMethods2007/08III.IntroductiontoStatisticsBasicstatisticalcommandsImportingdataPlottingdataCalculatingstatisticalmeasurementsusingmatlabformulaeandMatlabbuiltinfunctions.BasicstatisticalcommandsWehaveseen,intheprevioustutorials,thebasicmatrixoperationsandthemainplottingfunctions.Thisweek,wewillintroducethebasicstatisticalcommandsfunctionswhicharebrieflydescribedhere.MEANAverageormeanvalue.Forvectors,MEAN(X)isthemeanvalueoftheelementsinX.Formatrices,MEAN(X)isarowvectorcontainingthemeanvalueofeachcolumn.ForN-Darrays,MEAN(X)isthemeanvalueoftheelementsalongthefirstnon-singletondimensionofX.MEDIANMedianvalue.Forvectors,MEDIAN(X)isthemedianvalueoftheelementsinX.Formatrices,MEDIAN(X)isarowvectorcontainingthemedianvalueofeachcolumn.ForN-Darrays,MEDIAN(X)isthemedianvalueoftheelementsalongthefirstnon-singletondimensionofX.VARVariance.Forvectors,Y=VAR(X)returnsthevarianceofthevaluesinX.Formatrices,YisarowvectorcontainingthevarianceofeachcolumnofX.ForN-Darrays,VARoperatesalongthefirstnon-singletondimensionofX.VARnormalizesYbyN-1,whereNisthesamplesize.ThisisanunbiasedestimatorofthevarianceofthepopulationfromwhichXisdrawn,aslongasXconsistsofindependent,identicallydistributedsamples.Y=VAR(X,1)normalizesbyNandproducesthesecondmomentofthesampleaboutitsmean.VAR(X,0)isthesameasVAR(X).STDStandarddeviation.Forvectors,Y=STD(X)returnsthestandarddeviation.Formatrices,Yisarowvectorcontainingthestandarddeviationofeachcolumn.ForN-Darrays,STDoperatesalongthefirstnon-singletondimensionofX.STDnormalizesYby(N-1),whereNisthesamplesize.ThisisthesqrtofanunbiasedestimatorofthevarianceofthepopulationfromwhichXisdrawn,aslongasXconsistsofindependent,identicallydistributedsamples.Y=STD(X,1)normalizesbyNandproducesthesquarerootofthesecondmomentofthesampleaboutitsmean.STD(X,0)isthesameasSTD(X).CORRCOEFCorrelationcoefficients.R=CORRCOEF(X)calculatesamatrixRofcorrelationcoefficientsforanarrayX,inwhicheachrowisanobservationandeachc
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