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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116
｜
第
4
章
主效应
预测变量和结果变量之间的关系，该关系独立于其他的变量。
交互作用
两个或两个以上预测变量和响应之间的相互依赖关系。
4.5.1
相关的预测变量
在多元回归中，预测变量通常是相互关联的。例如，下面查看一下
4.2.4
节中拟合的
step_
lm
模型的回归系数。
step_lm$coefficients
(Intercept) SqFtTotLiving
6.227632e+06 1.865012e+02
Bathrooms Bedrooms
4.472172e+04 -4.980718e+04
BldgGrade PropertyTypeSingle Family
1.391792e+05 2.332869e+04
PropertyTypeTownhouse SqFtFinBasement
9.221625e+04 9.039911e+00
YrBuilt
-3.592468e+03
我们看到，
Bedrooms
的回归系数竟然是负值。这意味着在房子中增加一间卧室，反而会降
低房屋的价值。为什么会发生这种情况？这是因为预测变量是相互关联的。面积大的房子
一般有更多的卧室，而房屋的价值受面积大小的影响，而非卧室的数量。对于两个面积相
同的房子，我们更喜欢的通常不是卧室更多但面积更小的那个。
如果预测变量是相互关联的，那么回归系数的符号和值会难以解释（并且会提高估计量的
标准误差）。卧室、房屋面积和卫生间数量等变量就是相关的。下面的例子展示了这一关
联。我们在回归方程中移除了 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.