October 2021
Intermediate to advanced
289 pages
8h 31m
Chinese
Content preview from 数据科学中的实用统计学(第2版)
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60
｜
第
2
章
图 2-11：从标准正态分布中抽取包含 100 个值的样本的 QQ 图
将数据转换为
z
分数（即对数据进行标准化或归一化）并不能使数据服从
正态分布，这只能使数据与标准正态分布处于同一尺度，通常是为了进行
比较。
本节要点
•
在统计学发展史中，正态分布占有极其重要的地位，因为它可以对不确定性和变异
性进行数据近似。
•
尽管原始数据通常不是正态分布的，但误差通常是正态分布的，大样本中的均值和
总数也是如此。
•
要想把数据转换为
z
分数，需要先减去均值，再除以标准差。然后，可以将数据与
正态分布进行比较。
2.7
长尾分布
虽然正态分布在统计学历史中非常重要，但恰恰与它的名称相反，数据通常是不服从正态
分布的。
数据与抽样分布
｜
61
本节关键术语
尾
频数分布中长且窄的部分，其中相对极端的值的出现频数很低。
偏斜
分布一端的尾部长于另一端的尾部。
对于误差和样本统计量，通常适合使用正态分布来进行分析，但原始数据一般不服从正态
分布。有时候，原始数据的分布是高度
偏斜
（不对称）的，比如收入数据；分布也可能是
离散的，比如二项式数据。不论分布对称与否，它们都可能具有
长尾
特性。分布的尾部对
应于极端值（极大或极小）。在实际工作中，长尾现象非常普遍，其防范措施也备受关注。
纳西姆
•
塔勒布提出了
黑天鹅
理论，该理论预测异常事件 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.