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.
老师您好，在我们上课的时候在举例子讲授这个知识点的时候说的是confidence level 上升，区间会变宽。为什么答案是变窄？请问那个答案是正确的呢？
