CorrelationAnalysis.ppt

correlationcoefficient0.4-0.7=moderateand0.8-1.0=strongcorrelation,vignette,supposethereisalinearrelationshipbetweenageofcppatientsinthesampledatawith66patientsandsbp,examinethisrelationshipandinterpretyourresults.,analysis,spssanalysis,spssanalysis,spssoutput,spssanalysis-spearman,spssoutputspearmansrho,interpretation,inasampleof66childrenwithcp,thereisnosignificantrelationshipbetweenageofthechildrenandsystolicbp,r=0.02,p=0.90.assumingnon-normaldistributionofeitheroneofthevariables,anon-parametrictestwasused(spearmanrankcorrelation),r=0.025,p=0.84.ineithertest,thereisnolinearrelationshipbetweenageatsurgeryandthesbpofthesepatients.howevertheabsenceofalinearassociationdoesnotruleoutanon-linearrelationshipbetweentheageofthesepatientsandtheirsbp.,simplelinearregression,stats101,slrdoesisnotameasureofassociationbutlinearrelationship,absenceofasignificantassociationinslrdoesnotimplyabsenceofnon-linearassociation.,regressionmodel,statisticaltechniqueforassessingtherelationshipbetweendependentandoneormoreindependentvariabletherelationshipbetweentwovariablesischaracterizedbyhowtheyvarytogether.givenpairsofxandyvariables,regressionanalysismeasuresthedirection(positiveandnegative)andtherateofchangeinyasxchanges(slope),regressionmodel,adequateforpredictingthevalueofy,givenxinappropriateforassessingthestrengthofanassociationbetweentwoormorevariablescausalassociationassumed,simpleregressionmodel,regressionequationandlinerepresentthesimplelinearequationanddescribetheshapeoftherelationshipbetweenthevariables.regressionlineisthelinedrawnthroughscatterplotthattestthefitnessoftheregressionmodellikethecoefficientofdeterminationinthemodel,basicassumptions,linearitytherelationshipbetweenyandxislinear(straightlinerelationship)residualsareindependentandnormallydistributedhomosedasticity-thevarianceoftheresidualsisequalforallxthereisnomeasurementerroronx(impracticalassumption)-z-+-gm_wt|3200.8995422.6657.3480.00000.swilkgestationalageinweeksshapiro-wilkwtestfornormaldatavariable|obswvzprobz-+-gestationks|3200.8000445.1128.9690.00000.,sktestgm_wtgestationalageinweeksskewness/kurtosistestsfornormality-joint-variable|obspr(skewness)pr(kurtosis)adjchi2(2)probchi2-+-gm_wt|3200.00000.922329.740.0000gestationks|3200.00000.0000.0.0000.,iswt(gm)normallydistributed?,isgestationalage(wks)normallydistributed?,regression(output)&equation,regressgm_wtgestationalageinweeksifn_catgesta=1,vce(robust)linearregressionnumberofobs=78f(1,76)=445.12probf=0.0000r-squared=0.8849rootmse=320.37-|robustgm_wt|coef.std.err.tp|t|95%conf.interval-+-gestationks|102.3134.84944521.100.00092.65446111.9715_cons|-2546.343207.273-12.280.000-2959.163-2133.523,weight=-2546.3+102.3grams(gestationalageinweeks),regressionline,equation,rsquare,whatisrsquare?,interprettheregressionequation,vignette,inchildrenwithcpwhounderwentspinalfusionforcurvedeformitiescorrection,canpostoperativecobbanglebeusedinpredictingtheirlengthofhospitalization?whatistheregressionequation?pleaseinterpretyourresult.,scatterplot,istherealinearrelationshipfromthisplot?,slr:spss,ignore,resultinterpretation,theresultfromslrstatesthedirection,strength,value,degreesoffreedomandsignificancelevel.notethatifanovaisnotsignificant,thesectionoftheoutputlabeledsigwillbe0.05,implyingthattheregressionequationisnotsignificant.statementofresult:asimplelinearregressionwascomputedpredictingcpchildrenslengthofhospitalstayfollowingspinalfusionbasedontheirpostoperativecobbangle.theregressionequationwasnotsi