Week 3 내용

Central Tendency

Central Tendency (집중경향)
Dispersion (variability) – 분산(변산성)
range
outliers: It is beyond our scope. Please just refer to it. Won't be appearing in tests.
Variance 분산 혹은 변량
- 표본변량 $ s^2 $
- 모집단변량(전집) $ \sigma^2 $
Standard Deviation 표준편차
Variance calculation formula
- variance_calculation_formula $ \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 $
Degrees of Freedom N-1
- Why n-1