问题如下:
When sampling size is 50 with mean is 78, and population variance is unknown, which of the following distribution is taken if sampling forms a normal distribution?
选项:
A.z-statistic only
B.both t or z statistic
C.t-statistic only
解释:
B is correct, when sampling form a normal distribution with unknown variance, if sample size is larger than 30, both t or z-statistic is choose.
方差已知用z 方差未知用t,还有最后一句话是两个检验方法都不适用,是怎么说来着?有点忘了