Tse0507 · 2020年07月23日
问题如下：
The table below shows the monthly stock returns of Ivy Corp.
According to the above table, calculate the median stock return for Ivy Corp.?
选项：
A.7.7%.
B.8.0%.
C.12.0%.
解释：
B is correct
Firstly, we rank the returns : 20% 12% 12% 4% 3% -5%.
As there are 6 observations, the median is the average of 12% and 4%
(12%+4%)/2=8%.
为什么不是用分位数的公式？6乘以1/2=3.5，第三个数和第四个数是4和12，然后（12-4）乘以0.5，再加3，等于7，谢谢
星星_品职助教 · 2020年07月23日
同学你好，
当看到题目要求算中位数时，不应该用分位点的思路，因为中位数有自己的思路如下：
In an odd numbered sample of n items, the median occupies the (n + 1)/2 position. In an even-numbered sample, we define the median as the mean of the values of items occupying the n/2 and (n + 2)/2 positions (the two middle items).
答案解析即应用这种思路，考试遇到类似的题目直接仿照即可。
但这道题出的确实不大好，正常用分位点的公式算出来的结果应该是一样的。
NO.PZ2015120604000045问题如下 The table below shows the monthly storeturns of Ivy Corp.Accorng to the above table, calculate the mestoreturn for Ivy Corp.?A.7.7%.B.8.0%.C.12.0%.B is correctFirstly, we rank the returns : 20% 12% 12% 4% 3% -5%.there are 6 observations, the meis the average of 12% an4%(12%+4%)/2=8%.6个数，中位点是6+1=7/2=3.5中位数=4%+（12%-4%）*（3.5-3）=8%这种方法对吗？
NO.PZ2015120604000045 问题如下 The table below shows the monthly storeturns of Ivy Corp.Accorng to the above table, calculate the mestoreturn for Ivy Corp.? A.7.7%. B.8.0%. C.12.0%. B is correctFirstly, we rank the returns : 20% 12% 12% 4% 3% -5%.there are 6 observations, the meis the average of 12% an4%(12%+4%)/2=8%. 求mean，数据个数是偶数，不应该=n+2 / 2=4 ?
me要先排序的吗，那为什么求frequency的mean不用排序，按照给定的柱状图的frequency来求了
排序也应该是从小到大排序吧，虽然结果是一样的？？
