September 2013
Intermediate to advanced
264 pages
5h
Chinese
Content preview from Bad Data 技術手冊
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完整（Complete）
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225
一定不同。這沒什麼。我們並不希望 4C 成為一個普遍且無懈可擊的方法，而是希望將
其視為一個討論的起始點，並且是建立你自己的資料品質政策和程序的結構。
完整（Complete）
一個
完整
的資料集合的概念是很難以確定的。太容易會說出「它是一個擁有所有東西的
資料集合」這種話，然後就繼續往下作。但我們在這邊要如何定義「所有東西」？它單
純是記錄的數量嗎？預期的欄位計數？也許我們應該要包括所有的欄位都要擁有值—假
設「缺少值」本身並不是一個值（這尚未包含所有的值是否是正常的；那是之後會講到
的「正確性」的部分）。這讓我們開始學習哪些欄位是必要的，而哪些是可要的。
多數的這類問題是從相同的根源而來，而這對資料中的完整性是非常自然的：
我是否擁有所有需要用來回答我的問題的資料
？
就算是這樣仍然是需要技巧的：在你知道資料是否足夠之前，首先你通常必須要使用資
料來嘗試回答你的問題，然後驗證任何的結果。你也許能夠良好的執行這個「詢問然後
驗證」的遞迴。關鍵在於，你應該使用你的分析的首輪來確認完整性，並且盡可能的將
任何發現視為初步結果。這讓你不會在發現資料不完整之前，就在不成熟的結論上採取
行動。
讓我們從最簡單但常常被忽略的完整性開始：你真的擁有特定查詢的
所有
記錄嗎？若你
在包含有限且定義良好的記錄數量的資料上執行任何種類的分析，這是一個基本且不可
或缺的問題，並且總數（例如，訂單的數量，或是佣金的總和，或是總註冊學生）要跟
一些外部系統是一樣的，這件事也是重要的。試想為你最大的客戶，呈現一個在股票交 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.