110 121 95 92 109 98 104 1110 方差齐性检验 VSH1:o1≠ 两组方差齐性的检验命令(仅适合两组方差齐性检验) sdtest x, by (group) Variance ratio test Group Mean Std. Err. Std. Dev. [95% Conf. Interval] 25 1.8229289.1146485.3176692.84234 101.521.9009829.50491197.59657105.4434 combined I 95.31.57745611.154392.1299898.47002 Ho: sd(0)=sd(1) F(24, 24)observed F obs 0.920 F(24, 24) lower tail FL=F obs 0.920 F(24, 24)upper tail=FU =1/F obs 087 Ha: sd (0)< sd(1) d(0)=sd(1) Ha: sd(0)>sd(1) P<Fobs=0.4195 P<FL+P>FU=0.8389 p>F obs =0. 580 P值=0.8389>α,因此可以认为两组方差齐性的
1 98 1 110 1 89 1 103 1 89 1 121 1 94 1 95 1 92 1 109 1 98 1 98 1 120 1 104 1 110 方差齐性检验 H0：1＝2 vs H1:12 =0.1 两组方差齐性的检验命令(仅适合两组方差齐性检验) sdtest x,by(group) Variance ratio test ------------------------------------------------------------------------------ Group | Obs Mean Std. Err. Std. Dev. [95% Conf. Interval] ---------+-------------------------------------------------------------------- 0 | 25 89.08 1.822928 9.11464 85.31766 92.84234 1 | 25 101.52 1.900982 9.504911 97.59657 105.4434 ---------+-------------------------------------------------------------------- combined | 50 95.3 1.577456 11.1543 92.12998 98.47002 ------------------------------------------------------------------------------ Ho: sd(0) = sd(1) F(24,24) observed = F_obs = 0.920 F(24,24) lower tail = F_L = F_obs = 0.920 F(24,24) upper tail = F_U = 1/F_obs = 1.087 Ha: sd(0) < sd(1) Ha: sd(0) ~= sd(1) Ha: sd(0) > sd(1) P < F_obs = 0.4195 P < F_L + P > F_U = 0.8389 P > F_obs = 0.5805 P 值=0.8389>>，因此可以认为两组方差齐性的
正态性检验:Ho:资料服从正态分布vsH1:资料偏态分布 =0.05 每一组资料正态性检验 sktest x if group==0 Ske /Kurtosis tests for Normali Jo int Variable Pr(Skewness) Pr(Kurtosis) adj chi2(2) Prob>chi2 0.927 0.326 1.05 0.5926 sktest x if group==l Skewness/Kurtosis tests for Normality Variable Pr(Skewness) Pr(Kurtosis) adj chi2 (2) Pr 0.474 0.675 0.6948 P值均大于α,因此可以认为两组资料都服从正态分布 Ho:μu1=μ2vsH1:1≠2 =0.05 ttest x, by(group Two-sample t test with equal variances Group Mean Std. Err. Std. Dev. [95% Conf. Interval 9.1146485.3176692.84234 101.521.9009829.50491197.59657105.4434 combined 95.31.57745611.154392.1299898.47002 diff I 12.442.633781 -17.73557-7.144429 Degrees of freedom: 48 Ho: mean(0)- mean(1)= diff =0 Ha: diff < o Ha: diff=0 a: diff>0 4.7232 t=-4.7232 t=-4.7232 P< t 0.0000 P>|t|=0.0000 P>t 1.0000
正态性检验：H0：资料服从正态分布 vs H1：资料偏态分布 =0.05 每一组资料正态性检验 sktest x if group==0 Skewness/Kurtosis tests for Normality ------- joint ------ Variable | Pr(Skewness) Pr(Kurtosis) adj chi2(2) Prob>chi2 -------------+------------------------------------------------------- x | 0.927 0.326 1.05 0.5926 . sktest x if group==1 Skewness/Kurtosis tests for Normality ------- joint ------ Variable | Pr(Skewness) Pr(Kurtosis) adj chi2(2) Prob>chi2 -------------+------------------------------------------------------- x | 0.474 0.675 0.73 0.6948 P 值均大于，因此可以认为两组资料都服从正态分布 H0：1＝2 vs H1：12 =0.05 ttest x,by(group) Two-sample t test with equal variances ------------------------------------------------------------------------------ Group | Obs Mean Std. Err. Std. Dev. [95% Conf. Interval] ---------+-------------------------------------------------------------------- 0 | 25 89.08 1.822928 9.11464 85.31766 92.84234 1 | 25 101.52 1.900982 9.504911 97.59657 105.4434 ---------+-------------------------------------------------------------------- combined | 50 95.3 1.577456 11.1543 92.12998 98.47002 ---------+-------------------------------------------------------------------- diff | -12.44 2.633781 -17.73557 -7.144429 ------------------------------------------------------------------------------ Degrees of freedom: 48 Ho: mean(0) - mean(1) = diff = 0 Ha: diff < 0 Ha: diff ~= 0 Ha: diff > 0 t = -4.7232 t = -4.7232 t = -4.7232 P < t = 0.0000 P > |t| = 0.0000 P > t = 1.0000