NO.PZ2018062016000115 问题如下 If analyst want to crease the wih of the confininterval, whiof the following statement shoulselecte A.increase sample varian B.increase number of observations C.increase confinlevel B is correct, if number of observation become larger, sample varianis smaller, the wih of confinintervbecome smaller.观察的次数越多，样本方差越小，置信区间的宽度越小。 confininterval=point estimate ± reliability factor × stanrerror如果方差变大， 标准差也会同乡变大， 上面公式里面的减数变大， 所以wih变小， 那么A为什么会是错的

NO.PZ2018062016000115问题如下 If analyst want to crease the wih of the confininterval, whiof the following statement shoulselecteA.increase sample varianB.increase number of observationsC.increase confinlevel B is correct, if number of observation become larger, sample varianis smaller, the wih of confinintervbecome smaller.观察的次数越多，样本方差越小，置信区间的宽度越小。 根据公式，N越大，或者方便越小，置信区间越小啊

NO.PZ2018062016000115问题如下If analyst want to crease the wih of the confininterval, whiof the following statement shoulselecteA.increase sample varianB.increase number of observationsC.increase confinlevel B is correct, if number of observation become larger, sample varianis smaller, the wih of confinintervbecome smaller.观察的次数越多，样本方差越小，置信区间的宽度越小。 看了一遍其他的解答，那C是错在哪儿呢

NO.PZ2018062016000115问题如下If analyst want to crease the wih of the confininterval, whiof the following statement shoulselecteA.increase sample varianB.increase number of observationsC.increase confinlevel B is correct, if number of observation become larger, sample varianis smaller, the wih of confinintervbecome smaller.观察的次数越多，样本方差越小，置信区间的宽度越小。 我理解，公式s/root of n中的n是sample size。现在题目中说的是number of observations变多，sample size只是取样的数，不一定会变大，那么依据公式，confininterval也不一定会变窄吧？

NO.PZ2018062016000115 问题如下 If analyst want to crease the wih of the confininterval, whiof the following statement shoulselecte A.increase sample varian B.increase number of observations C.increase confinlevel B is correct, if number of observation become larger, sample varianis smaller, the wih of confinintervbecome smaller.观察的次数越多，样本方差越小，置信区间的宽度越小。 不是应该样本容量越多，试错越多，信心程度越高吗