问题如下:
Suppose a hypothesis test with a 5% significant level. What is the critical value of a z-statistic if it is a two-tailed test?
选项:
A.±1.65
B.±1.96.
C.+1.96
解释:
B is correct.
A two-tailed z-test at a 5% significant level means the critical value is z=-1.96 or z=+1.96.
请问如果是单尾检验,critical value是正负还是只有一个?