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
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
27
27
2.9 効果量
するときに使います。詳しくは
8
章（「
8.2
分散を予測する」）で説明します。
pandas
のデータ構造には、平均、分散、標準偏差を計算するメソッドがあります。
mean = live.prglngth.mean()
var = live.prglngth.var()
std = live.prglngth.std()
すべての生児出生について、平均妊娠期間は
38.6
週、標準偏差は
2.7
週で、これ
は
2
〜
3
週の変動が普通であると予期すべきだということです。
妊娠期間の分散は
7.3
ですが、これは、単位が週の
2
乗、つまり「平方週」になる
ことから特に解釈が困難です。分散はある種の計算には有用ですが、要約統計量とし
ては不適です。
2.9
効果量
効果量（
effect size
）は、（望んでいる）効果の大きさを記述するための要約統計
量です。例えば、
2
つのグループの違いを記述するためなら、平均の差を使うのが普
通です。
第一子の平均妊娠期間は
38.601
週、第二子以降は、
38.523
週です。差は
0.078
週
ですから、
13
時間です。典型的な妊娠期間に対する割合としては、この差は約
0.2%
です。
この推定が正しいとしても、このような差は実用上は意味を持ちません。実際、多
数の妊娠を観察しない限り、この差に気付く人は誰もいないでしょう。
効果量を伝える他の方式に、グループ間の差をグループ全体の変動性と比較するや
り方があります。コーエンの
d
（
Cohen's d
）はそのような統計量で、次のように定
義されます。 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.