NO.PZ2015120601000013
问题如下：
An analyst stated that, all else equal, increasing sample size will decrease both the standard error and the width of the confidence interval. The analyst’s statement is correct in regard to:
选项：
A.
both the standard error and the confidence interval.
B.
the standard error, but incorrect in regard to the confidence interval.
C.
the confidence interval, but incorrect in regard to the standard error.
解释：
A is correct.
All else equal, a larger sample size will decrease both the standard error and the width of the confidence interval. In other words, the precision of the estimate of the population parameter is increased.
在其他条件相同的情况下，更大的样本量将同时降低标准误和置信区间的宽度。 换句话说，增加了总体参数估计的精度。
为什么confidence interval 会变小？
