SAS带解释.docx
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SAS带解释.docx
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SAS带解释
例1用频率表法对下表数据,计算频数分布
138名正常成年女子的红细胞数
频数分布
组段
频数
组中值
(1)
(2)
(3)
(4)=
(2)×(3)
(5)=
(2)×(3)2
3.07~
2
3.17
6.34
20.10
3.27~
3
3.37
10.11
37.07
3.47~
9
3.57
32.13
114.70
3.67~
14
3.77
52.78
198.98
3.87~
22
3.97
87.34
346.74
4.07~
30
4.17
125.10
521.67
4.27~
21
4.37
91.77
401.03
4.47~
15
4.57
68.55
313.27
4.67~
10
4.77
47.70
227.53
4.87~
6
4.97
29.82
148.21
5.07~
4
5.17
20.68
106.92
5.27~5.47
2
5.37
10.74
57.67
合计
138
—
583.06
2493.89
dataa;
inputfx;/*x为中位数*/
cards;
23.17
33.37
93.57
143.77
223.97
304.17
214.37
154.57
104.77
64.97
45.17
25.37
;
procunivariatenormalplot;
freqf;
varx;
run;
结果:
TheUNIVARIATEProcedure
Variable:
x
Freq:
f
Moments
N138SumWeights权重和138
Mean4.22507246SumObservations583.06
StdDeviation0.44738861Variance方差0.20015656
Skewness偏度0.22418477Kurtosis峰度-0.0193013
UncorrectedSS未校正平方和2490.8922CorrectedSS校正平方和27.4214493
CoeffVariation变异系数10.5888978StdErrorMean标准误0.03808425
BasicStatisticalMeasures
LocationVariability
Mean均数4.225072StdDeviation标准差0.44739
Median中位数4.170000Variance方差0.20016
Mode众数4.170000Range极差2.20000
InterquartileRange四分位间距0.60000
TestsforLocation:
Mu0=0
Test-Statistic------pValue------
Student'stt检验t110.9402Pr>|t|<.0001
Sign符号检验M69Pr>=|M|<.0001
SignedRank符号秩检验S4795.5Pr>=|S|<.0001
例2配对数据的均值比较----配对T检验(步骤同配对样本差值的Wilcoxon符号秩和检验)
用克矽平治疗矽肺患者,治疗前后血红蛋白含量如下表,问能否认为治疗前后血红蛋白的含量有所不同?
治疗前:
113150150135128100110120130123
治疗后:
140138140135135120147114138120
dataa;
inputx1x2;
d=x1-x2;
cards;
113140
150138
150140
135135
128135
100120
110147
120114
130138
123120
;
procunivariatenormal;
vard;
run;
TheUNIVARIATEProcedure
Variable:
d
TestsforLocation:
Mu0=0
Test-Statistic------pValue------
Student'st(t检验)t-1.30662Pr>|t|0.2237
SignM-0.5Pr>=|M|1.0000
SignedRank(符号秩和)S-8.5Pr>=|S|0.3594
TestsforNormality差值d的正态性检验
Test--Statistic--------pValue------
Shapiro-WilkW0.925147Pr Kolmogorov-SmirnovD0.170937Pr>D>0.1500 Cramer-vonMisesW-Sq0.052954Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.326814Pr>A-Sq>0.2500 因为Shapiro-Wilk正态性检验得出P>0.10(a宜稍大以减少第Ⅱ类错误),可以认为治疗前后血红蛋白的含量差值d服从正态分布,进行t检验。 1.建立检验假设,确定检验水准 H0: μd=0,治疗前后血红蛋白的含量的总体均数为0(秩和检验时,H0: Md=0,差值的总体中位数为0) H1: μd≠0,治疗前后血红蛋白的含量的总体均数不为0 a=0.05 2.计算检验统计量由SAS计算得出t=-1.30662,v=10-1=9 3.确定P值,作出推断 P=0.2237>0.05,在a=0.05的水准上接受H0,尚不能认为治疗前后血红蛋白的含量差值不同。 例3两独立样本的t检验(同Satterthwaite近似t检验) 研究者将40名糖尿病人,随机分配到试验组和对照组应用降糖药物,测得空腹血糖下降值(mmol/L),能否认为试验药物和对照药物对空腹血糖的降糖效果不同? 试验组X1: -0.70-5.602.002.800.703.504.005.807.10-0.50 2.50-1.601.703.000.404.504.602.506.00-1.40 对照组X2: 3.706.505.005.200.800.200.603.406.60-1.10 6.003.802.001.602.002.201.203.101.70-2.00 dataaa; inputx@@; if_n_<21thenc=1; elsec=2; cards; -0.70-5.602.002.800.703.504.005.807.10-0.50 2.50-1.601.703.000.404.504.602.506.00-1.40 3.706.505.005.200.800.200.603.406.60-1.10 6.003.802.001.602.002.201.203.101.70-2.00 ; procunivariatenormal; varx; classc; run; procttest; varx; classc; run; TheUNIVARIATEProcedure Variable: x c=1 TestsforNormality试验组x1的正态性检验 Test--Statistic--------pValue------ Shapiro-WilkW0.969895Pr Kolmogorov-SmirnovD0.106519Pr>D>0.1500 Cramer-vonMisesW-Sq0.028187Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.207507Pr>A-Sq>0.2500 TheUNIVARIATEProcedure Variable: x c=2 TestsforNormality对照组x2的正态性检验 Test--Statistic--------pValue------ Shapiro-WilkW0.970979Pr Kolmogorov-SmirnovD0.119689Pr>D>0.1500 Cramer-vonMisesW-Sq0.031687Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.212563Pr>A-Sq>0.2500 TheTTESTProcedure T-Tests VariableMethodVariancesDFtValuePr>|t| xPooledEqual方差齐38-0.640.5248 xSatterthwaiteUnequal方差不齐36.1-0.640.5250 EqualityofVariances方差齐性检验 VariableMethodNumDFDenDFFValuePr>F xFoldedF19191.600.3153 从题意看出,试验组与对照组的血糖下降量为两独立小样本的比较。 经SAS软件统计检验,可认为试验组与对照组血糖下降量来自正态总体(P>0.1),而且方差相等(P>0.1)。 符合两独立样本t检验的条件。 1.建立检验假设,确定检验水准 H0: μ1=μ2,试验组与对照组的血糖下降量的总体均数相等 H1: μ1≠μ2,试验组与对照组的血糖下降量的总体均数不等 a=0.05 2.计算检验统计量由SAS计算得出t=-0.64,v=2×(20-1)=38 3.确定P值,作出推断 P=0.5248>0.05,在a=0.05的水准上接受H0,尚不能认为试验药物和对照药物对空腹血糖的降糖效果不同 例4对10例肺癌病人和12例矽肺0期工人用X光片测量肺门横径右侧距RD值(cm),结果见表8-5。 问肺癌病人的RD值是否高于矽肺0期工人的RD值? 肺癌病人RD值: 2.783.234.24.875.126.217.188.058.569.6 矽肺0期工人RD值: 3.233.54.044.154.284.344.474.644.754.82 4.955.1 dataaa; inputxc@@; cards; 2.781 3.231 4.201 4.871 5.121 6.211 7.181 8.051 8.561 9.601 3.232 3.502 4.042 4.152 4.282 4.342 4.472 4.642 4.752 4.822 4.952 5.102 ; procunivariatenormal; varx; classc; run; procttest; varx; classc; run; procnpar1waywilcoxon; varx; classc; run; TheUNIVARIATEProcedure Variable: x c=1 TestsforNormality Test--Statistic--------pValue------ Shapiro-WilkW0.959034Pr Kolmogorov-SmirnovD0.144509Pr>D>0.1500 Cramer-vonMisesW-Sq0.028191Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.190257Pr>A-Sq>0.2500 TheUNIVARIATEProcedure Variable: x c=2 TestsforNormality Test--Statistic--------pValue------ Shapiro-WilkW0.942621Pr Kolmogorov-SmirnovD0.121633Pr>D>0.1500 Cramer-vonMisesW-Sq0.039329Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.286254Pr>A-Sq>0.2500 TheTTESTProcedure EqualityofVariances VariableMethodNumDFDenDFFValuePr>F xFoldedF91116.84<.0001 两样本资料经统计检验,推断得肺癌病人和矽肺0期工人的RD值来自正态总体,但是两总体方差不等,可以用Wilcoxon秩和检验(注: 也可以用近似t检验,但一般不考近似t检验)。 TheNPAR1WAYProcedure WilcoxonScores(RankSums)forVariablex ClassifiedbyVariablec SumofExpectedStdDevMean cNScoresUnderH0UnderH0Score ----------------------------------------------------------------- 110141.50115.015.16146914.150000 212111.50138.015.1614699.291667 Averagescoreswereusedforties. WilcoxonTwo-SampleTest Statistic141.5000(样本例数小者的秩和) NormalApproximation Z1.7149 One-SidedPr>Z0.0432(专业知识判断用单侧检验) Two-SidedPr>|Z|0.0864 tApproximation One-SidedPr>Z0.0505 Two-SidedPr>|Z|0.1011 Zincludesacontinuitycorrectionof0.5 1.建立检验假设,确定检验水准 H0: 肺癌病人和矽肺0期工人的RD值总体分布位置相同 H1: 肺癌病人RD值高于矽肺0期工人的RD值 a=0.05 2.计算检验统计量由SAS计算得出T=141.5,n1=10,n2-n1=2。 3.确定P值,作出推断 单侧P=0.0432<0.05,在a=0.05的水准上拒绝H0,接受H1,肺癌病人RD值高于矽肺0期工人的RD值。 例5多组样本均数比较的方差分析 研究降血脂药,120名患者随机分到4组用药,1组安慰剂组,其余3组分别为2.4g组,4.8g组,7.2g组。 问4个处理组的低密度脂蛋白含量总体均数有无差别? “数据略”例4-2 dataaa; inputxc@@; cards; 3.5312.4222.8630.894 4.5913.3622.2831.064 4.3414.3222.3931.084 2.6612.3422.2831.274 3.5912.6822.4831.634 3.1312.9522.2831.894 3.3012.3623.4831.314 4.0412.5622.4232.514 3.5312.5222.4131.884 3.5612.2722.6631.414 3.8512.9823.2933.194 4.0713.7222.7031.924 1.3712.6522.6630.944 3.9312.2223.6832.114 2.3312.9022.6532.814 2.9811.9822.6631.984 4.0012.6322.3231.744 3.5512.8622.6132.164 2.6412.9323.6433.374 2.5612.1722.5832.974 3.5012.7223.6531.694 3.2511.5623.2131.194 2.9613.1122.2332.174 4.3011.8122.3232.284 3.5211.7722.6831.724 3.9312.8023.0432.474 4.1913.5722.8131.024 2.9612.9723.0232.524 4.1614.0221.9732.104 2.5912.3121.6833.714 ; procunivariatenormal;/*正态性检验*/ varx; classc; run; procanova; classc; modelx=c; meansc/dunnett;/*多组均数的两两比较*/ meansc/hovtest; run; TheUNIVARIATEProcedure Variable: x c=1 TestsforNormality Test--Statistic--------pValue------ Shapiro-WilkW0.952294Pr Kolmogorov-SmirnovD0.138803Pr>D0.1439 Cramer-vonMisesW-Sq0.06523Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.420853Pr>A-Sq>0.2500 Variable: x c=2 TestsforNormality Test--Statistic--------pValue------ Shapiro-WilkW0.966675Pr Kolmogorov-SmirnovD0.139168Pr>D0.1415 Cramer-vonMisesW-Sq0.058496Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.368941Pr>A-Sq>0.2500 Variable: x c=3 TestsforNormality Test--Statistic--------pValue------ Shapiro-WilkW0.944498Pr Kolmogorov-SmirnovD0.165062Pr>D0.0362 Cramer-vonMisesW-Sq0.118633Pr>W-Sq0.0623 Anderson-DarlingA-Sq0.699903Pr>A-Sq0.0636 Variable: x c=4 TestsforNormality Test--Statistic--------pValue------ Shapiro-WilkW0.958332Pr Kolmogorov-SmirnovD0.092484Pr>D>0.1500 Cramer-vonMisesW-Sq0.041802Pr>W-Sq>0.2500 Anderson-DarlingA-Sq0.330124Pr>A-Sq>0.2500 推断得出四组数据来自正态总体 TheANOVAProcedure ClassLevelInformation ClassLevelsValues c41234 NumberofObservationsRead120 NumberofObservationsUsed120 TheANOVAProcedure DependentVariable: x Sumof(方差分析表) SourceDFSquares(SS)MeanSquareFValuePr>F Model(组间)332.1560300010.7186766724.88<.0001 Error(组内)11649.967020000.43075017 CorrectedTotal(总变异)11982.12305000 R-SquareCoeffVarRootMSExMean 0.39155924.285500.6563162.702500 SourceDFAnovaSSMeanSquareFValuePr>F c332.1560300010.7186766724.88<.0001 tTests(LSD)forx NOTE: ThistestcontrolstheTypeIcomparisonwiseerrorrate,nottheexperimentwiseerrorrate. Alpha0.05 ErrorDegreesofFreedom116 ErrorMeanSquare0.43075 CriticalValueoft1.98063 LeastSignificantDifference0.3356 Meanswiththesameletterarenotsignificantlydifferent. tGroupingMeanNc A3.4303301 B2.7153302 B B2.6980303 C1.9663304 Levene'sTestforHomogeneityofxVariance ANOVAofSquaredDeviationsfromGroupMeans SumofMean(多组的方差齐性) SourceDFSquaresSquareFValuePr>F c
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