c:ms:2017:schedule:week03
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c:ms:2017:schedule:week03 [2017/04/05 08:06] – hkimscil | c:ms:2017:schedule:week03 [2022/05/15 11:25] (current) – [Central Tendency] hkimscil | ||
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- | ====== Week 3 내용 ====== | + | ㄹ====== Week 3 내용 ====== |
===== SPSS ===== | ===== SPSS ===== | ||
< | < | ||
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* [[:Standard Deviation]] 표준편차 | * [[:Standard Deviation]] 표준편차 | ||
- | * Variance calculation formula | + | * Variance calculation formula |
- | * {{anchor: | + | * $ \displaystyle S_x^2 = \displaystyle \frac {\Sigma X^2 - \frac{(\Sigma X)^2}{N} } {N-1} $ |
- | * $\displaystyle \sigma_x^2 = \displaystyle \frac {\Sigma X^2 - \frac{(\Sigma X)^2}{N} } {N} = \displaystyle \frac {\Sigma X^2}{N} - \frac {(\Sigma X)^2}{N^2} = \displaystyle \frac {\Sigma X^2}{N} - \bigg(\frac {\Sigma X}{N}\bigg)^2 = \displaystyle \frac {\Sigma X^2}{N} - \mu^2 | + | * $ \displaystyle \sigma_x^2 = \displaystyle \frac {\Sigma X^2 - \frac{(\Sigma X)^2}{N} } {N} = \displaystyle \frac {\Sigma X^2}{N} - \frac {(\Sigma X)^2}{N^2} = \displaystyle \frac {\Sigma X^2}{N} - \bigg(\frac {\Sigma X}{N}\bigg)^2 = \displaystyle \frac {\Sigma X^2}{N} - \mu^2 $ |
* [[:Degrees of Freedom]] N-1 | * [[:Degrees of Freedom]] N-1 | ||
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와 같다. | 와 같다. | ||
- | 이렇게 얻은 샘플들(k 개의)의 평균인 $A_k$ 는, | + | 이렇게 얻은 샘플들(k 개의)의 평균인 $ A_k $ 는, |
- | $$A_k = \displaystyle \frac{(X_1 + X_2 + . . . + X_k)}{k} = \frac{S_{k}}{k} $$ | + | $$ A_k = \displaystyle \frac{(X_1 + X_2 + . . . + X_k)}{k} = \frac{S_{k}}{k} $$ |
라고 할 수 있다. | 라고 할 수 있다. | ||
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이때, | 이때, | ||
- | $$ | + | $$ |
\begin{align*} | \begin{align*} | ||
E[S_k] & = E[X_1 + X_2 + . . . +X_k] \\ | E[S_k] & = E[X_1 + X_2 + . . . +X_k] \\ | ||
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$$ | $$ | ||
- | $$ | + | $$ |
\begin{align*} | \begin{align*} | ||
Var[S_k] & = Var[X_1 + X_2 + . . . +X_k] \\ | Var[S_k] & = Var[X_1 + X_2 + . . . +X_k] \\ | ||
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이다. | 이다. | ||
- | 그렇다면, | + | 그렇다면, |
- | $$ | + | $$ |
\begin{align*} | \begin{align*} | ||
E[A_k] & = E[\frac{S_k}{k}] \\ | E[A_k] & = E[\frac{S_k}{k}] \\ |
c/ms/2017/schedule/week03.1491348970.txt.gz · Last modified: 2017/04/05 08:06 by hkimscil