# statistical methods

## Statisticalmethods

Statisticsarerichandintricate,anditisnoteasytoselectstatisticalanalysismethodsreasonably.Forthesamedata,ifyouchoosedifferentstatisticalanalysismethods,sometimestheconclusionsarecompletelydifferent.

Thebasisforthecorrectchoiceofstatisticalmethodis:

①Accordingtothepurposeoftheresearch,clarifythetypeofresearchexperimentdesign,researchfactorsandlevelnumber;

②DeterminethedataCharacteristics(whethernormaldistribution,etc.)andsamplesize;

Finally,accordingtotheactualsituationofprofessionalknowledgeanddata,combinedwithstatisticalprinciples,thestatisticalanalysismethodshouldbeflexiblyselected.

## Statisticalclassification

1Statisticalmethodsofmeasurementdata

Statisticalanalysismethodsforanalyzingmeasurementdatacanbedividedintoparametrictestmethodsandnon-parametrictestmethods.

Parametertestingmethodsaremainlyt-testandanalysisofvariance(ANOVA,F-test),etc.Thet-testandu-testarecommonlyusedwhencomparingmeansbetweentwogroups,andtheanalysisofvarianceiscommonlyusedwhencomparingmeansabovetwogroups.;Non-parametrictestmethodsmainlyincluderanksumtestandsoon.Thettestcanbedividedintothettestofsinglegroupdesigndata,thettestofpaireddesigndataandthettestofgroupdesigndata;whentwosmallsamplesarecompared,thetwopopulationdistributionsarerequiredtobenormallydistributedandthevariancesarehomogeneous.IfnotTomeettheaboverequirements,anon-parametricmethod(ranksumtest)shouldbeused.Theanalysisofvariancecanbeusedtocomparethemeanoftwoormoresamples.Whenapplyingthismethod,eachsampleisrequiredtobeamutuallyindependentrandomsample,eachsamplecomesfromanormalpopulationandtheoverallvarianceofeachtreatmentgroupishomogeneous.Accordingtodifferentdesigntypes,therearemanydifferentmethodsintheanalysisofvariance.Forquantitativedata,appropriatestatisticalanalysismethodsshouldbeselectedaccordingtothetypeofdesignused,theconditionsofthedataandthepurposeofanalysis,andt-testandone-wayanalysisofvarianceshouldnotbeblindlyapplied.

2Statisticalmethodsofcountingdata

Thestatisticalmethodsofcountingdataaremainlyusedfortheanalysisofthefour-gridtableandtheR×Ctable

test.Fourgridtabledata:use