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b:head_first_statistics:variability_and_spread

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Variability and Spread

Who are you going to use for the upcoming game (basketball)?

A
7 8 9 10 11 12 13
1 1 2 2 2 1 1
B
7 9 10 11 13
1 2 4 2 1
C
3 6 7 10 11 13 30
2 1 2 3 1 1 1
a <- c(7,8,9,9,10,10,11,11,12,13)
b <- c(7,9,9,10,10,10,10,11,11,13)
c <- c(3,3,6,7,7,10,10,10,11,13,30)
## c <- c(3,3,6,7,7,10,11,13,15,20,30)

data <- list(a,b,c)
data
sapply(data,mean)
sapply(data,median)
sapply(data,range)

sapply(data,sd)
sapply(data,var)
> a <- c(7,8,9,9,10,10,11,11,12,13)
> b <- c(7,9,9,10,10,10,10,11,11,13)
> c <- c(3,3,6,7,7,10,10,10,11,13,30)
> 
> data <- list(a,b,c)
> data
[[1]]
 [1]  7  8  9  9 10 10 11 11 12 13

[[2]]
 [1]  7  9  9 10 10 10 10 11 11 13

[[3]]
 [1]  3  3  6  7  7 10 10 10 11 13 30

> sapply(data,mean)
[1] 10 10 10
> sapply(data,median)
[1] 10 10 10
> sapply(data,range)
     [,1] [,2] [,3]
[1,]    7    7    3
[2,]   13   13   30
>
>
> sapply(data,sd)
[1] 1.825742 1.563472 7.362065
> sapply(data,var)
[1]  3.333333  2.444444 54.200000
> 

range

quartile
variance

  • $ \sum \text{deviation score}^2 = \sum \text{ds}^2 $
  • $ \sum \text{error}^2 $
    • error = 평균값으로 개인값을 추측했을 때 발생하는 오차
    • (평균으로 추측했을 때 생기는) 오차의 제곱의 합
    • (오차의) 제곱의 합
    • 제곱의 합
    • Sum of Square (SS)
  • $ \sum \text{ds}^2 = \text{SS} = \text{Sum of Square} $ 1)
  • $$ \text{variance} = \frac {SS}{n-1} = \frac {SS}{df}$$
  • calculation of variance (an easy way) see variance calculation
    • $ \displaystyle \frac{\sum(X_{i})}{N} - \mu^2$

standard deviation
standard score

1)
표준오차_잔여변량_standard_error_residual의 Figure 1을 보면 x와 y가 모두 숫자로 측정된 변인일 때, Y의 평균만을 사용해서 Y값을 예측했을 때는 SStotal이라고 설명한다.
b/head_first_statistics/variability_and_spread.1600659415.txt.gz · Last modified: 2020/09/21 12:36 by hkimscil

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