October 2018
Beginner to intermediate
238 pages
6h 32m
Chinese
Content preview from 面向数据科学家的实用统计学
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64
｜
第
3
章
A/B
测试有
对象
，对象会分配给两组处理中的一组。对象可能是一个人、一种植物种子
或一位
Web
访问者。注意，对象需要接受处理。在理想情况下，对象是
随机指定
（即随
机分配）给一组处理的。这样，两个实验组之间的任何差异，只可能是由下面两个因素
所导致的。
•
不同处理的效果。
•
将对象分配到不同处理过程中的运气因素。一些对象的效果本来就很好，而随机分配可
能会导致效果好的对象集中在处理
A
或处理
B
中。
在
A/B
测试中，我们也需要关注比较
A
组和
B
组时使用的
检验统计量
（即度量）。在数据
科学中，最常用的度量可能是二元变量，例如点击或未点击，购买或不购买，作弊或未作
弊，等等。我们可以将比较结果归纳为一个
2
×
2
的表格。表
3-1
给出了实际价格测试结果
的一个
2
×
2
的表格。
表3-1：电子商务实验结果的2
×
2表格
结果 价格
A
价格
B
点击转化为购买
200 182
点击没有转化为购买
23 539 22 406
在比较中所使用的度量，可以是连续变量（例如购买数量、利润等），也可以是计数（例
如住院天数、访问的页面数量）。两者的结果显示存在着差异。如果关注的并非点击广告
的转化情况，而是每次页面浏览的收益情况，那么在常见的软件输出中，表
3-1
的价格测
试结果大致如下。
Revenue/page-view with price A: mean = 3.87, SD = 51.10
Revenue/page-view with price B: mean = 4.11, SD = 62.98
结果中的
SD
表示的是各组中值的标准偏差。 ...
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