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R aov和t.test提供不同的结果_R_Anova - Fatal编程技术网

R aov和t.test提供不同的结果

R aov和t.test提供不同的结果,r,anova,R,Anova,据我所知,当应用于具有一个解释变量的数据时,t检验应提供与方差分析相同的结果(相同的p值)。为了测试这一点,我运行了以下命令来比较结果: df <- structure(list(y = c(1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1), x = structure(c(1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("FP", "WP" ), class = "factor")), class = "da

据我所知,当应用于具有一个解释变量的数据时,t检验应提供与方差分析相同的结果(相同的p值)。为了测试这一点,我运行了以下命令来比较结果:

df <- structure(list(y = c(1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1), x = structure(c(1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("FP", "WP" ), class = "factor")), class = "data.frame", row.names = c(NA,-11L))

summary(aov(y ~ x, data = df))
             Df Sum Sq Mean Sq F value Pr(>F)
x            1 0.3068  0.3068   1.473  0.256
Residuals    9 1.8750  0.2083               

t.test(y ~ x, data = df)

Welch Two Sample t-test

data:  y by x
t = -2.0494, df = 7, p-value = 0.0796
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
 -0.80768193  0.05768193
sample estimates:
mean in group FP mean in group WP 
           1.000            1.375 
df)
x10.30680.30681.4730.256
残差9 1.8750 0.2083
t、 测试(y~x,数据=df)
韦尔奇双样本t检验
数据:y乘x
t=-2.0494,df=7,p值=0.0796
替代假设:平均值的真实差异不等于0
95%置信区间:
-0.80768193  0.05768193
样本估计:
FP组平均值WP组平均值
1.000            1.375 
可以看出,方差分析的p值为0.256,t检验的p值为0.0796

为了理解这种偏差的原因,我自己计算了测试统计数据,使用了a和for的公式。当组的大小不同时,t-test函数似乎给出了错误的结果


是否有设置使t-test能够正确处理不同的组大小?

结果没有错误,
t-test
功能仅在两组的方差不相等时应用。可以按如下方式抑制此操作:

t.test(y ~ x, data = df, var.equal = TRUE)

    Two Sample t-test

data:  y by x
t = -1.2136, df = 9, p-value = 0.2558
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
 -1.0740253  0.3240253
sample estimates:
mean in group FP mean in group WP 
           1.000            1.375 
它给出了与方差分析相同的p值(请注意,输出的标题现在不是“Welch双样本t-test”,而是简单的“双样本t-test”)