问题
单项选择题
Hypothesis test can be divided into one-tailed test and two-tailed test. A onetailed hypothesis test may not have a:（）
A. "Iess than or equal to" alternative hypothesis.
B. "not equal to" alternative hypothesis.
C. "greater than" alternative hypothesis.
答案
参考答案：B
解析：
双边检验的原假设为“equal to”，备择假设为“not equal to”，拒绝域在两边。单边检验的备择假设可以是“less than”或“greater than”，也可以是“less than or equal to”或“great than or equal to”，因为在连续分布的情况下，落在具体某一个点的概率为0。