where n1 is the size of first sample; n2 is the size of second sample; m1 is the mean of first sample; m2 is the mean of second sample
t = (m1 - m2) / sqrt(var1/n1 + var2/n2)
n1 is the size of the first sample n2 is the size of the second sample; m1 is the mean of the first sample; m2 is the mean of the second sample; var1 is the variance of the first sample; var2 is the variance of the second sample;
Student's t-tests. https://zh.wikipedia.org/wiki/%E5%AD%B8%E7%94%9Ft%E6%AA%A2%E9%A9%97
双总体t检验是检验两个样本平均数与其各自所代表的总体的差异是否显著。双总体t检验又分为两种情况，一是独立样本t检验，一是配对样本t检验。 独立样本t检验统计量为： t = (m1 - m2) / (sqrt(1/n1 +1/n2) sqrt(var)) var = sqrt(((n1 - 1)var1 + (n2 - 1)var2) / ((n1-1) + (n2-1)))
where n1 is the size of first sample; n2 is the size of second sample; m1 is the mean of first sample; m2 is the mean of second sample
t = (m1 - m2) / sqrt(var1/n1 + var2/n2)
n1 is the size of the first sample n2 is the size of the second sample; m1 is the mean of the first sample; m2 is the mean of the second sample; var1 is the variance of the first sample; var2 is the variance of the second sample;