NO.PZ2015120604000144
问题如下：
Quintina conducts a hypothesis to test whether the variance of the annually return is 0.0144. Then she selects a random 25 year's data as a sample, Quintina figures out the variance of the sample is 0.013924. Assume the level of significance is 5%, which of the following conclusion is least accurate?
选项：
A. The population variance is not significant different from 0.0144.
B. The population variance is significantly different from 0.0144.
C. This hypothesis is appropriate to use the chi-square test.
解释：
B is correct.
The null hypothesis is H0: σ2=0.0144. It is appropriate to use the two-tailed chi-square test.
The test statistic is:
=(25-1)*0.013924/0.0144=23.21
The critical chi-square critical values are 12.4 and 39.36.
Because the test statistic falls between these two values,so Quintina fails to reject the null hypothesis.
So we conclude that the population variance is not significantly different from 0.0144.
题干是问which is the least accurate?所以选B。
这道题chi square 测试值算出来了，用（n-1）s²/q².但是查表怎么查，这道题没有给出critical value范围。
