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粗眉毛辣椒油 · 2024年02月03日

IQR

NO.PZ2020010304000036

问题如下:

For the following data:

a. What is the median?

b. What is the IQR?

选项:

解释:

a. The first step is to rank order the observations.

From here, we anchor the first observation at 0% and the last at 100%, equally spacing the in-between val-ues. The divisions here will be 100/n-1 = 20%:

The median (50%) lies exactly half way between the third and fourth ranked observations. Therefore:

Median=(0.28+0.38)/2=0.33

b. This requires calculating the 25% and 75% levels.

The 25% level is 5/20 = 25% of the way between ranked observations 2 and 3. Therefore: q25% = 0.75 * 0.27 + 0.25 * 0.28 = 0.2725

Similarly, the 75% level is 75% of the way between observations 4 and 5: q75% = 0.25 * 0.38 + 0.75 * 0.43 = 0.4175

Thus, IQR = (0.2725, 0.4175).

应该怎么求?没看懂解析。

2 个答案
已采纳答案

pzqa27 · 2024年02月04日

嗨,努力学习的PZer你好:


25到20的距离是5,25到40的距离是15,20到40的距离一共是20,那么20的value就占75%,40的value就占25%。线性插值法其实就是个名称而已,实质不难理解。

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努力的时光都是限量版,加油!

pzqa27 · 2024年02月04日

嗨,努力学习的PZer你好:


这个题要求我们计算IQR,IQR是找到25%的分位点和75%的分位点。

因此通过观察题目表格可知,25%的分位点在第二个value和第三个value之间,因此需要用到线性插值法来计算。

25%的分位点距离20%更近,离40%更远,因此20%分位点的0.27取75%,40%分位点的0.28取0.25,所以25%分位点是0.75 * 0.27 + 0.25 * 0.28 = 0.2725

同理可以计算75%分位点是0.75 * 0.27 + 0.25 * 0.28 = 0.2725

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努力的时光都是限量版,加油!

粗眉毛辣椒油 · 2024年02月04日

请问线性插值法是一个考点吗?课上讲过吗?

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NO.PZ2020010304000036问题如下For the following ta:Whis the mean? Whis the IQR?The first step is to rank orr the observations.From here, we anchor the first observation 0% anthe last 100%, equally spacing the in-between val-ues. The visions here will 100/n-1 = 20%:The me(50%) lies exactly half wbetween the thiranfourth rankeobservations. Therefore:Mean=(0.28+0.38)/2=0.33 This requires calculating the 25% an75% levels.The 25% level is 5/20 = 25% of the wbetween rankeobservations 2 an3. Therefore: q25% = 0.75 * 0.27 + 0.25 * 0.28 = 0.2725Similarly, the 75% level is 75% of the wbetween observations 4 an5: q75% = 0.25 * 0.38 + 0.75 * 0.43 = 0.4175Thus, IQR = (0.2725, 0.4175). 老师,这种方式也叫插分吗?

2024-05-13 16:04 1 · 回答

NO.PZ2020010304000036正常情况下不是默认取这6个数的概率相同吗,那每个数应该是100%/6,我认为第一个数应该是有概率的

2022-06-23 13:57 1 · 回答

NO.PZ2020010304000036 求分位点分母为什么是n-1?

2022-03-19 15:40 1 · 回答

NO.PZ2020010304000036 做题思路都是默认第一个数的概率是0%,然后其余的数平分100%的概率,并按照从小到大和累计概率来排序,是这样吗? 假如这道题是11个数,那么升序排列后概率依次为0%、10%······100%, (假如还是这些数)四分之一分位点就是q25%=0.27*50%+0.28*50%=0.275; 或者用线性差值法来做(x-0.27)/(0.28-0.27)=(25%-20%)/(30%-20%) 辛苦老师解答!

2022-02-18 18:05 1 · 回答