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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数据与抽样分布
｜
43
图 2-3：准星偏离的枪的射击散点图
偏差有多种形式，有的可以观测，有的不可观测。当一个结果确实表现出偏差时（例如，
通过参考某个基准或实际的值），通常说明统计模型或机器学习模型存在着错误设定，或
者丢掉了某个重要变量。
2.1.2
随机选择
样本偏差导致《文学文摘》得出兰登会战胜罗斯福的预测结果。为了避免这种问题，乔
治
•
盖洛普（见图
2-4
）使用了更加科学的选择方法，以获取一个能代表美国大选投票人的
样本。现在有各种各样的方法可以保证样本的代表性，但所有方法的核心都是
随机抽样
。
图 2-4：乔治
•
盖洛普，因为《文学文摘》的“大数据”失败事件而一战成名
随机抽样并非总是轻而易举，对可用总体的正确定义是关键。如果我们想生成一份有代表
性的客户档案，就需要进行一次试验性的客户调查。这种调查必须是有代表性的，但需要
大量的人力。
首先，需要定义目标客户。我们可以选出所有购买金额大于
0
的客
户记录，但需要包括以
前的所有客户吗？需要包括那些已退款的客户吗？代理商呢？收款代理人也算客户吗？
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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.