过儿 · 2022年04月10日
NO.PZ2015120604000051
问题如下：
The table below shows part of the monthly stock returns of Ivy Corp.
Calculate the sample variance for Ivy Corp. returns, assuming above table inclues all samples.
选项：
A.8.78%.
B.64.2%2.
C.77.1%2.
解释：
C is correct
= [(20 - 7.7)2 + (4 - 7.7)2 + (-5- 7.7)2 + (12- 7.7)2 + (3 - 7.7)2 + (12- 7.7)2] / (6-1) = 77.1%2
计算器SX=1.192651
O-x=1.0887，
用0.887的平方可以得出78.67，
提问1.：样本减1个自由度是吗，是算整个population的标准差，那一个除以6，一个除以5，要是算population，用小得坟墓，算出来的两个数字，应该是大的那个才对，为什么不是sx，SX这里代表什么呢。
NO.PZ2015120604000051 问题如下 The table below shows part of the monthly storeturns of Ivy Corp.Calculate the sample varianfor Ivy Corp. returns, assuming above table inclues all samples. A.8.78%. B.64.2%2. C.77.1%2. C is correctsamplevariance=∑(X−μ)2n−1sample\quvariance=\fr{ { \sum { (X-\mu ) } }^{ 2 } }{ n-1 }samplevariance=n−1∑(X−μ)2= [(20 - 7.7)2 + (4 - 7.7)2 + (-5- 7.7)2 + (12- 7.7)2 + (3 - 7.7)2 + (12- 7.7)2] / (6-1) = 77.1%2 \"百分号的平方 = 原单位百分号进行平方后的结果 这是一种特殊的表述方式。\"每逢计算sample variance都要用这个特殊的百分号平方吗?请问百分号平方是代表什么?进行计算sample variance是不是不用理会这个特殊的百分号平方吗?谢谢
NO.PZ2015120604000051 问题如下 The table below shows part of the monthly storeturns of Ivy Corp.Calculate the sample varianfor Ivy Corp. returns, assuming above table inclues all samples. A.8.78%. B.64.2%2. C.77.1%2. C is correctsamplevariance=∑(X−μ)2n−1sample\quvariance=\fr{ { \sum { (X-\mu ) } }^{ 2 } }{ n-1 }samplevariance=n−1∑(X−μ)2= [(20 - 7.7)2 + (4 - 7.7)2 + (-5- 7.7)2 + (12- 7.7)2 + (3 - 7.7)2 + (12- 7.7)2] / (6-1) = 77.1%2 这句话体现的是样本Calculate the sample varianfor Ivy Corp. returns, 但又提到表中包含了全部样本，是否意味着表中的数据就是总体assuming above table inclues all samples.
NO.PZ2015120604000051 问题如下 The table below shows part of the monthly storeturns of Ivy Corp.Calculate the sample varianfor Ivy Corp. returns, assuming above table inclues all samples. A.8.78%. B.64.2%2. C.77.1%2. C is correctsamplevariance=∑(X−μ)2n−1sample\quvariance=\fr{ { \sum { (X-\mu ) } }^{ 2 } }{ n-1 }samplevariance=n−1∑(X−μ)2= [(20 - 7.7)2 + (4 - 7.7)2 + (-5- 7.7)2 + (12- 7.7)2 + (3 - 7.7)2 + (12- 7.7)2] / (6-1) = 77.1%2 老师好，为什么计算机按到SX得到8.78之后需要再平方？然后为什么答案C-77.1%后面也跟着个平方？SX求出来的是属于什么？所以，SX，SX的平方，SX的平方的平方分别求出来的都是什么？
NO.PZ2015120604000051 问题如下 The table below shows part of the monthly storeturns of Ivy Corp.Calculate the sample varianfor Ivy Corp. returns, assuming above table inclues all samples. A.8.78%. B.64.2%2. C.77.1%2. C is correctsamplevariance=∑(X−μ)2n−1sample\quvariance=\fr{ { \sum { (X-\mu ) } }^{ 2 } }{ n-1 }samplevariance=n−1∑(X−μ)2= [(20 - 7.7)2 + (4 - 7.7)2 + (-5- 7.7)2 + (12- 7.7)2 + (3 - 7.7)2 + (12- 7.7)2] / (6-1) = 77.1%2 这道题我用stata 算的的时候发现 n=7我想知道有什么方式可以不用clethe work 使n=6 呢，我返回ta界面不知道怎么去改 X7=0 这个input
NO.PZ2015120604000051 问题如下 The table below shows part of the monthly storeturns of Ivy Corp.Calculate the sample varianfor Ivy Corp. returns, assuming above table inclues all samples. A.8.78%. B.64.2%2. C.77.1%2. C is correctsamplevariance=∑(X−μ)2n−1sample\quvariance=\fr{ { \sum { (X-\mu ) } }^{ 2 } }{ n-1 }samplevariance=n−1∑(X−μ)2= [(20 - 7.7)2 + (4 - 7.7)2 + (-5- 7.7)2 + (12- 7.7)2 + (3 - 7.7)2 + (12- 7.7)2] / (6-1) = 77.1%2 第一步，7.7是从这些里面求出的算术平均数吗？
