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Ariel · 2023年01月18日

怎么区分置信间，好像还有一个正态抽样前的置信区间是（u-1.65标准差 u+1.65标准差）

  1. CFA I
  2. Quantitative

NO.PZ2015120604000130

问题如下：

We want to use z-statistic to construct confidence interval for a normally distribution. Assume the sample size is 100, sample mean is 15% and the standard deviation of sample is 25%. The significance level is supposed to be 10% , the confidence interval is :

选项：

A.

- 10.88% to 19.13%.

B.

10.88% to 19.13%.

C.

10.88% to 20.57%.

解释：

B is correct.

In this case, we can know that the Confidence Interval=[Point Estimate +/- (reliability factor)*Standard error]=


什么时候会考这个区间，一般问这个区间的问题是怎么问的

这个区间的标准差指的是总体标准差吗

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已采纳答案

星星_品职助教 · 2023年01月18日

同学你好，

如果是针对总体做置信区间，则中心是μ，对应的是总体标准差σ。就是提问中的“u-1.65标准差 u+1.65标准差”。

如果是针对样本均值做置信区间，则中心是样本均值 X bar，对应的也是X bar的标准差，即标准误。标准误的公式为s / 跟号n。也就是答案解析中的形式。

考试的定量题目一般都是要求根据公式来做置信区间的相关计算。例如求置信区间，求出上区间端点值，计算区间宽度等等。

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