请教如何用鉴定的方法判断两组数据的平均值大小？

知道用T-test可以鉴定两组数据的平均值是否相等，但若是想判断哪组数据的平均值大，哪组数据的平均值小用什么方法呢？可否用单尾的P-value值判断大小呢？T-test结果如下：
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F-Test Two-Sample for Variances

yield(before) yield(after)
Mean 0.950903304 0.956951461
Variance 0.000297305 0.00020767
Observations 98 98
df 97 97
F 1.431623213
P(F<=f) one-tail 0.039399277
F Critical one-tail 1.398866187

t-Test: Two-Sample Assuming Unequal Variances

yield(before) yield(after)
Mean 0.950903304 0.956951461
Variance 0.000297305 0.00020767
Observations 98 98
Hypothesized Mean Difference 0
df 188
t Stat -2.664410645
P(T<=t) one-tail 0.004191242
t Critical one-tail 1.652999113
P(T<=t) two-tail 0.008382485
t Critical two-tail 1.972662649