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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107
8
章
推定
†
8.1
推定ゲーム
これからゲームをしましょう。私が頭に思い描く分布について、それがどのような
ものかを当ててください。ヒントを
2
つあげましょう。それは正規分布です。そして、
そこから無作為に抽出した標本を次に示します。
[-0.441, 1.774, -0.101, -1.138, 2.975, -2.138]
この分布の平均母数（パラメータ）μはいくつだと思いますか
?
μを求める
1
つの方法は、標本平均
x
-
を使ってμを推定するというものです。こ
の例では
x
-
は
0.155
ですから、μ＝
0.155
と推測するのが妥当でしょう。この過程が
推定（
estimation
）と呼ばれ、ここで使う統計量（標本平均）が推定量（
estimator
、
推定関数）
‡
と呼ばれます。
μの推定に標本平均を使うのは自明なので、この他にも適切な方法があるとはなか
なか思えません。しかし、外れ値を導入してゲームを変えてみましょう。
ある分布を考えています。それは正規分布です。ここに信頼のおけない検査員が集
めた標本があります。この人は小数点を間違った位置に付けてしまうことがあります。
[-0.441, 1.774, -0.101, -1.138, 2.975, -213.8]
μの推定値（
estimate
）はいくつでしょうか。標本平均を使うと、μの値は
†
本章のコードは、
estimation.py
にある。コードのダウンロードや扱い方については、
viii
ページの 「コー
ドを使う」を参照してほしい。
‡
訳注：推定量は、推定した数値そのものではなく ...
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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.