Differences

This shows you the differences between two versions of the page.

--- variability_and_spread [2019/09/24 10:27] – hkimscil
+++ variability_and_spread [2019/09/30 20:27] (current) – removed hkimscil
@@ Line 1: / Line 1: @@
-====== 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  | 8  | 10  | 11  | 13  |
-| 1  | 2  | 4  | 2  | 1   |
-^  C  ^^^^^^^
-| 3  | 6  | 7  | 10  | 11  | 13  | 30  |
-| 2  | 1  | 2  | 3  | 1  | 1  | 1  |
-<code>
-a <- c(7,8,9,9,10,10,11,11,12,13)
-b <- c(7,8,8,10,10,10,10,11,11,13)
-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,sd)
-sapply(data,var)
-</code>
-<code>
-> data
-[[1]]
- [1]  7  8  9  9 10 10 11 11 12 13
-[[2]]
- [1]  7  8  8 10 10 10 10 11 11 13
-[[3]]
- [1]  3  3  6  7  7 10 10 10 11 13 30
-> sapply(data,mean)
-[1] 10.0  9.8 10.0
-> sapply(data,sd)
-[1] 1.825742 1.751190 7.362065
-> sapply(data,var)
-[1]  3.333333  3.066667 54.200000
-</code>
-[[:range]]
-[[:quartile]]
-[[:variance]]
-  * $ \sum \text{deviation score}^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} $
-  * $$ \text{variance} = \frac {SS}{n-1} = \frac {SS}{df}$$
-  * calculation of variance (an easy way)
-[[:standard deviation]]
-[[:standard score]]