扩大样本不应该使得置信区间增大吗问题如下图：
选项：
A. 
B. 
C. 
解释：
NO.PZ2018062001000013 问题如下 Tim, analyst of investment company, says \"If we increase the sample size only, both the stanrerror anthe confinintervwih will rece. \" Tim's statement is: A.correct. B.incorreabout confininterval. C.incorreabout the stanrerror. A is correct.increasing the sample size, the estimation of population parameter is more accurate. Therefore, the stanrerror will crease, anconfinintervwill become narrower.通过增加样本量，总体参数的估计会更加准确。 因此，标准误会降低，置信区间会变窄。 置信度增加会使置信区间变窄吗？
NO.PZ2018062001000013问题如下Tim, analyst of investment company, says \"If we increase the sample size only, both the stanrerror anthe confinintervwih will rece. \" Tim's statement is: A.correct. B.incorreabout confininterval. C.incorreabout the stanrerror. A is correct.increasing the sample size, the estimation of population parameter is more accurate. Therefore, the stanrerror will crease, anconfinintervwill become narrower.通过增加样本量，总体参数的估计会更加准确。 因此，标准误会降低，置信区间会变窄。 对置信区间和置信度这个概念还是有点模糊
除了sample size大小以外，confininterval是不是也取决于confinlevel的大小？这里好像没有提及到这点，何老师上课好像还强调了这点。
不是当样本数量增加，N自由度也是增加，置信区间不是更宽吗？
