Percentile Points and ranks provide information about relative standing.
The median is the point below which 50% of scores fall
P.50
Let's use the median as an example since conceptually we already understand how to calculate it.

Here are 45 scores (N = 45):
34, 10, 11, 3, 4, 10, 12, 11, 7, 30, 9, 12, 16, 23, 14, 28, 15, 9, 8, 17, 6, 31, 3, 39, 12, 26, 24, 5, 12, 27, 13, 3, 6, 25, 19, 13, 4, 23, 2, 19, 11, 13, 17, 20, 14
First rank order the scores:
39 34 31 30 28 27 26 25 24 23 23 20 19 19 17 17 16 15 14 14 13 13 13 12 12 12 12 11 11 11 10 10 9 9 8 7 6 6 5 4 4 3 3 3 2

Because N is odd, the median is the (N +1) / 2 th score.
In this case the median is the 23rd score.
Since there is duplication around the median we will need to interpolate (i.e., take this duplication into account).
The 23rd score is the first score with a value of 13.
You should know how to do this.
Divide the interval into thirds (3 scores)
[size=-1]12.50 [size=+1]12.67[size=-1]12.83 [size=+1]13.00 [size=-1]13.16 [size=+1]13.33 [size=-1]13.50
Thus, the median = 12.67.

若能收集到该词条相关资料的跟帖者给予奖励，根据收集资料的水平给予5～100不等的论坛币，当然也可以谈谈自己的看法、应用背景，相关软件知识，上传资料等等都可以。请大家尽量不要复制一些搜索引擎很容易收集到的资料。

     我每天都会发送不等数量的词条，所以诚邀不同统计背景的各路大侠给予评论。

     欢迎大家多多跟帖！要数量也要质量哟