1. Measures of Central Tendency
- Statistic (ํต๊ณ๋) & Parameter (๋ชจ์)

- ํต๊ณ๋ : sample(ํ๋ณธ)์ ๋ฐ์ดํฐ ๊ฐ์ ์ฌ์ฉํ์ฌ ์ป์ ํน์ฑ ๋๋ ์ธก์ ๊ฐ
- ๋ชจ์ : ํน์ population(๋ชจ์ง๋จ)์ ๋ชจ๋ ๋ฐ์ดํฐ ๊ฐ์ ์ฌ์ฉํ์ฌ ์ป์ ํน์ฑ ๋๋ ์ธก์ ๊ฐ
Mean



: halfway point, midpoint
โ Exist outlier : median > mean
Mode
: Most often
Unimodal : only one mode
Bimodal : two modes
Multimodal : more than two modes
Midrange
: rough estimate of the middle
โ Outlier ์๋ค๋ฉด?
Weighted mean

k% trimmed mean
: ์์๊ฑฐ์์ k%, ํฐ๊ฑฐ์์ k% ๋นผ๊ณ 100-2k%๋ก๋ง ํ๊ท ์ ๊ณ์ฐ
Properties and uses of central tendency
- Relationships among the mean, median, and mode
- for a symmetric histogram

- skewed to the right

- skewed to the left

2. Measures of Variation
Range
Population variance and standard deviation
Sample variance and standard deviation
- basic formulas

- short-cut formulas

Variance and standard deviation for grouped data
Similar for finding the mean for grouped data
Ex_
The data represent the # of miles that 20 runners ran during one week

Coefficient of variation (๋ณ๋๊ณ์)
โ ๋น๊ต๋จ์๊ฐ ๋ค๋ฅด๊ธฐ ๋๋ฌธ์
Range rule for thumb
Be used to approximate the standard deviation
Chebyshevโs theorem



Ex_
The empirical (normal) rule
- For a bell shaped distribution, approximately
- 68% of the obs. lie within 1 std. of mean
- 95% of the obs. lie within 2 std. of mean
- 99.7% of the obs. lie within 3 std. of mean
3. Measures of Position
Standard scores ( ํ์ค์ ์ )

โ ํ์ค์ ์๋ ๋ฐ์ดํฐ ๊ฐ์ด ํ๊ท ๋ณด๋ค ๋๊ฑฐ๋ ๋ฎ์ ํ์ค ํธ์ฐจ์ ์๋ฅผ ๋ํ๋ธ๋ค
Percentiles ( ๋ฐฑ๋ถ์์ )
โ ์ด๋ฌํ ๊ฐ ๋ถ๋ถ์๋ ์ฆ๊ฐํ๋ ์์๋ก ๋ฐฐ์ด๋ ๋ฐ์ดํฐ ์งํฉ์ ๊ด์ธก๊ฐ ์ค 1%๊ฐ ํฌํจ
Quartiles ( ์ฌ๋ถ์์ )

IQR ( Interquarile Range )
IQR=Q3โโQ1โ
Outlier ( ์ด์๊ฐ )
Exploratory Data Analysis (EDA)
- 5-number summary & Boxplots
- min, Q1โ, Q2โ , Q3โ , max

- Ex_
75 69 84 112 74 104 81 90 94 144 79 98
Construct a box-and-whisker plot for these data.



HGU GLSํ๋ถ ๊นํ์ฃผ ๊ต์๋์ 23-2 ํต๊ณํ ์์
์ ๋ฃ๊ณ ์์ฑํ ํฌ์คํธ์ด๋ฉฐ, ์ฒจ๋ถํ ๋ชจ๋ ์ฌ์ง์ ๊ต์๋ ์์
PPT์ ์ฌ์ง ์๋ณธ์ ํ๊ธฐ๋ฅผ ํ ์์ ๋ณธ์
๋๋ค.