卫生统计学stata练习题

期末作业汇报一、两独立样本：1、独立性：满足2、方差齐性检验：・sdtesty,by(group)VarianceratiotestGroup|LObsMeanStd.Err.Std.Dev.[95%Conf.Interval]十0129.0225572.56525783.044006—1・1353211.1804351|L162.415993・76094263.04377.79408214.037904十combined|45.8735565・48067863.22449—.09518761.842301Ho:sd(0)=sd(1)TOC\o"1-5"\h\zF(28,15)observed=F_obs=1.000F(28,15)lowertail=F_L=1/F_obs=1.000F(28,15)uppertail=FU=Fobs=1.000Ha:sd(0)<sd(1)Ha:sd(0)~=sd(1)Ha:sd(0)>sd(1)P<F_obs=0.4818P<F_L+P>F_U=0.9997P>F_obs=0.5182

由软件结果可知，P=0.9997>0.10，不能拒绝H/故可以认为方差齐性。3、正态性检验：.sktestyifgroup==0Skewness/KurtosistestsforNormalityjointVariable|Pr(Skewness)Pr(Kurtosis)adjchi2(2)Prob>chi21y|0.4530.8170.650.7241•sktestyifgroup==1joint

Variable|Pr(Skewness)Pr(Kurtosis)adjchi2(2)Prob>chi2+y10.0760.3974.150.1257由软件结果可知，两组的P值都大于0・05,故不能拒绝H0,可认为两组资料服从正态分布。4、t检验：由于资料满足独立性、方差齐性和正态性三个条件，故选择t检验。ttesty,by(group)Two-samplettestwithequalvariancesGroup|LObsMeanStd.Err.Std.Dev.[95%Conf.Interval]十0129.0225572.56525783.044006-1・1353211.1804351|L162.415993・76094263.04377・79408214.037904十combined|L45.8735565・48067863.22449-.09518761.842301十diff|-2.393436・9479405—4.30514-.4817315Degreesoffreedom:43Ho:mean(0)-mean(1)=diff=0Ha:diff<0Ha:diff~=0Ha:diff>0t=一2.5249t=一2.5249t=一2・5249P<t=0.0077P>|t|=0.0153P>t=0.9923由软件结果可知，P=0.0153<0.05,拒绝H0,接受H1,即两种药物治疗慢性肾炎的疗效不同；由于0组的样本均数(0・0225572)小于1组的样本均数(2.415993),故可推断B药的效果更好。5、秩和检验：・ranksumy,by(group)Two-sampleWilcoxonrank-sum(Mann-Whitney)testgroup|obsranksumexpectedT-01295556671|L16480368十combined|45103510351778.670.001778.670.00adjustedvarianceadjustedvariance1778.67Ho:y(group==0)=y(group==1)z=一2・656Prob>|z|=0.0079二、三个独立样本：1、独立性：满足2、方差齐性检验:ygroup;predicte,residual;genee=abs(e);onewayeegroup:onewayeegroupSourceSSdfMSFProb>FBetweengroups.0322453732.0161226870.030.9690Withingroups30.224460959.512278998Total30.256706261.496011578Bartlett'stestforequalvariances:chi2(2)=0.9884Prob>chi2=0.610由软件结果可知，P>0.10,方差齐性，下面进行正态性检验。3、正态性检验：swilkyifgroup==1VariableShapiro-WilkWtestfornormaldata|ObsLWVzProb>zy十|220.925081.8981.2990.09691swilkyifgroup==2Variable|ObsWVzProb>zy11170.964780.744-0.5890.72222swilkyifgroup==3Variable|ObsWVzProb>zchi-squaredwithties=chi-squaredwithties=33.000with1d.f.y|230.899432.6311.9670.02460由软件结果可知，第3组不满足正态性的要求，故选用K-W检验。4、K-W检验：chi-squared=probability=・kwallisy,by(group)chi-squared=probability=Test:Equalityofpopulations(Kruskal-Wallistest)group_Obs_RankSum122276.00217506.003231171.0051.070with2d.f.0.0001chi-squaredwithties=51.070bability=0.0001由软件结果可知，P<0・05,故三种药治疗慢性肾炎的有效率不全相同。5、两两比较：采用Bonferroni法，校正后的a=0・05/3=0.01667chi-squared=probability=kwallisyifgroup==1|group==2,by(group)chi-squared=probability=Test:Equalityofpopulations(Kruskal-Wallistest)group_Obs_RankSum122276.00217504.0021.574with1d.f.0.0001hi-squaredwithties=21.574with1d.f.robability=0.0001ifgroup==1group==3,by(group)ifgroup==1group==3,by(group)group_Obs_RankSumgroup_Obs_RankSum22253.00323782.00chi-squared=probability=33.000with1d.f.0.0001probability=0.0001ifgroup==2probability=0.0001ifgroup==2group==3,by(group)group_0bs_RankSum17155.00chi-squared=probability=23665.00chi-squared=probability=28.027with1d.f.0.0001chi-squaredwithties=28.027bability=0.0001由于每两组之间比较的P值都小于a，故可推断三种药治疗慢性肾炎的有效率都不相同。6、方差分析：・onewayygroupSourceAnalysisofVarianceSSdfMSFProb>FBetweengroups383.7919092191.895955148.750.0000Withingroups76.1134674591.29005877Total459.905377617・5394324Bartlett'stestforequalvariances:chi2(2)=0.3200Prob>chi2=0.8527、两两比较：・lsdygroupLSD方法进行两两均数比较

输入效应变量分组变量

mean1-mean2=-2.742864P-value=0.000000mean1-mean3=一5・836804P-value=0.000000mean2-mean3=-3.093940P-value=0.000000・onewayygroup,bSourceAnalysisofVarianceSSdfMSFProb>FBetweengroups383.7919092191.895955148.750.0000Withingroups76.1134674591.29005877Total459.905377617・5394324Bartlett'stestforequalvariances:chi2(2)=0.3200Prob>chi2=0.852Comparisonofybygroup(Bonferroni)RowMean-|ColMean|412+2|112.742860.0003|15.83680.0003.093940.000三、'配对资料1、独立性：数据独立，先考虑配对t检验2、正态性检验：gend=x1-x2swilkdShapiro-WilkWtestfornormaldataVariable|ObsWVzProb>z+d|320.983270.558-1・2110.88707由软件结果可知，差值服从正态分布，选用配对t检验。3、配对t检验：ttestd=0Variable|ObsMeanStd.Err.Std.Dev.[95%Conf.Interval]L十d|32-.3875.75401814.265371-1.925331.15033Degreesoffreedom:31Ho:mean(d)=0Ha:mean<0Ha:mean~=0Ha:mean>0

t=—0.5139t=—0.5139t=—0.5139P<t=0.3055P>|t|=0.6110P>t=0.6945由软件结果可知，P值＞0・05,不能拒绝H0,故不能认为这2种药物治疗高血脂的疗效不同。4、符号秩和检验：・signrankxl=x2Wilcoxonsigned-ranktestsign|obssumranksexpected+一positive|14236263・5negative|17291263.5zero|L111十all|32528528unadjustedvariance2860.00adjustmentforties—0.88adjustmentforzeros—0.25adjustedvariance2858.88Ho:x1=x2z=-0.514Prob>|z|=0.6070本题可直接采用秩和检验：ranksumy,by(group)group|obsranksumexpected十0I40138913601I27889918十combined|6722782278unadjustedvariance6120.00adjustmentforties—2070.00adjustedvariance4050.00Ho:y(group==0)=y(group==1)z=0.456Prob>|z|=0.6486

由软件结果可知，P值＞0.05，故不能认为两种药物的疗效有差别。五、本题可直接采用符号秩和检验:・signrankyl=y2sign|Lobssumranksexpected十positive|7689.51576negative|252462.51576zero|L8234033403十all|11465556555unadjustedvariance125091.25adjustmentforties-682.00adjustmentforzeros-46791.25adjustedvariance77618.00Ho:y1=y2z=—3.182Prob>|z|=0.0015由软件结果可知，P值<0.05,故两种药物的疗效不同。六、随机区组1、数据转换：stackx1blockx2blockx3block,into(yblock)2、方差齐性检验：anovaygroupblock;predicte,residual;genee=abs(e);anovaeegroupblock:・anovaeegroupblockNumberofobs=99R—squared=0.4773RootMSE=1.04435AdjR—squared=0.1996Total|133.547507981.36272967由软件结果可知，P<0.05,故方差不齐，采用Friedman检验。3、Friedman检验：friedmanblb2b3b4b5b6b7b8b9bl0bllbl2bl3bl4bl5bl6bl7bl8bl9b20b21b22b23b24b25b26b27b28b29b30b31b32b33Friedman=23.8636Kendall=0.3616p-value=0.0000由软件结果可知，P<0.05,故这3种药物治疗该疾病的疗效不同。4、方差分析：・anovaygroupblockNumberofobs=99R-squared=0.6244RootMSE=2.31064AdjR-squared=0.4248Source|LPartialSSdfMSFProb>F十Model|567.9478983416.70434993・130.0000group|171.420602285.710301116.050.0000block|396.5272953212.3914782.320.00211Residual|L341.699399645.33905311十Total|909.647296989.28211527七、相关性检验：・pwcorrxy,sig1Lxy十x|||1.0000y10.66341.000010.0000由软件结果可知，r=0.6634,P=0・0000<0.05,故pH0,因此，两个指标之间存在相关性。八、回归分析:

・regyxSource|SSdfMSNumberofobs=17(1aa\—46十F(1,44)—•Model|93832.6765193832.6765Prob>F—0.0000Residual|28.477749344・647221576R-squared—0.9997AQQQ7十Adjrsquared—0.9997Total|93861.1542452085.80343RootMSE—.8045y|Coef・Std.Err.tP>|t|[95%Conf.Interval]+x|4.961854.0130315380.760.0004.935594.988117_cons|2.488645.226470910.990・0002.0322222.945067由软件结果可知，y=2.49+4.96x。P值小于0.05,故该回归方程成立。九、本题釆用Logrank检验：・ststestgroupfailure_d:deadanalysistime_t:timeLog-ranktestforequalityofsurvivorfunctions|EventsEventsgroup|observedexpected10|3120.27

111727.731Total|4848.00chi2(1)=10.84Pr>chi2=0.0010由软件结果可知，两种药物的疗效不同。十、样本率与已知总体率的比较:・prtesti5060.15,countOne-sampletestofproportionx:Numberofobs=50Variable|LMeanStd.Err.zP>|z|[95%Conf.Interval]十X1.12・04595652.611160.0090.0299269.2100731Ho:proportion(x)=