August 2015
Intermediate to advanced
272 pages
5h 46m
Japanese
Content preview from Think Stats 第2版 ―プログラマのための統計入門
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197
197
13.3 生存曲線を推論する
>>> hf = sf.MakeHazard()
>>> hf[39]
0.49689
したがって、
39
週まで進んだ妊娠のうち、ほぼ
50 %
はその週内で終わります。
図
13-1
の下側は、妊娠期間のハザード関数を示します。
42
週を超えると、ハザー
ド関数は、わずかな事例に基づいているために、不安定になります。その他では、曲
線の形は期待どおりです。
39
週付近で最も高く、前半の方が後半よりも若干高くな
ります。
ハザード関数は、それ自体で有用ですが、次節以降で見るように、生存曲線の推定
にも重要なツールとなります。
13.3
生存曲線を推論する
生存期間の
CDF
が渡されたなら、生存関数やハザード関数の計算は容易です。し
かし、多くの実世界のシナリオでは、生存時間の分布を直接測定できません。推論し
なければならないのです。
例えば、診断後どれだけ長く生きているか、患者のグループを追跡しているものと
しましょう。すべての患者が同じ日に診断を受けたとは限りません。したがって、ど
の時点でも、他の人より長く生存している患者がいます。死んだ患者については、生
存期間がわかります。まだ生きている患者については、下限は知っていますが、生存
期間はまだわかりません。
すべての患者が死ぬまで待てば、生存曲線を計算できますが、新たな治療の効果を
評価しているのだとすれば、そんなに長くは待てません。不完全な情報を用いて生存
曲線を推定するやり方が必要です。
もっと心がなごむ例として、
NSFG
データを用いて、 ...
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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.