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ditto · 2023年11月11日

A哪里不对

NO.PZ2018062016000115

问题如下:

If analyst want to decrease the width of the confidence interval, which of the following statement should be selected.

选项:

A.

increase sample variance

B.

increase number of observations

C.

increase confidence level

解释:

B is correct, if number of observation become larger, sample variance is smaller, the width of confidence interval become smaller.

观察的次数越多,样本方差越小,置信区间的宽度越小。

confidence interval=point estimate ± reliability factor × standard error

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width变小, 那么A为什么会是错的

1 个答案

星星_品职助教 · 2023年11月11日

同学你好,

上面公式是“±”,不是减。所以是加的数和减的数都变大,这就导致置信区间变宽。

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