ベイズ統計モデリング 4.1

4.6 エクササイズ

show(HairEyeColor)

## , , Sex = Male
## 
##        Eye
## Hair    Brown Blue Hazel Green
##   Black    32   11    10     3
##   Brown    53   50    25    15
##   Red      10   10     7     7
##   Blond     3   30     5     8
## 
## , , Sex = Female
## 
##        Eye
## Hair    Brown Blue Hazel Green
##   Black    36    9     5     2
##   Brown    66   34    29    14
##   Red      16    7     7     7
##   Blond     4   64     5     8

性別全体の合計

eyeHairFreq = apply(HairEyeColor, c("Eye","Hair"), sum)
eyeHairFreq

##        Hair
## Eye     Black Brown Red Blond
##   Brown    68   119  26     7
##   Blue     20    84  17    94
##   Hazel    15    54  14    10
##   Green     5    29  14    16

同時比率(全体を1としたときの比率)

EyeHairProp = eyeHairFreq / sum(eyeHairFreq)
EyeHairProp

##        Hair
## Eye           Black      Brown        Red      Blond
##   Brown 0.114864865 0.20101351 0.04391892 0.01182432
##   Blue  0.033783784 0.14189189 0.02871622 0.15878378
##   Hazel 0.025337838 0.09121622 0.02364865 0.01689189
##   Green 0.008445946 0.04898649 0.02364865 0.02702703

性別と目の全体の合計

HairFreq = apply(HairEyeColor, c("Hair"), sum)
HairFreq

## Black Brown   Red Blond 
##   108   286    71   127

周辺確率(髪の色)

HairProp = HairFreq / sum(HairFreq)
HairProp

##     Black     Brown       Red     Blond 
## 0.1824324 0.4831081 0.1199324 0.2145270

性別と髪の全体の合計

EyeFreq = apply(HairEyeColor, c("Eye"), sum)
EyeFreq

## Brown  Blue Hazel Green 
##   220   215    93    64

周辺確率(目の色)

eyeProp = EyeFreq / sum(EyeFreq)
eyeProp

##     Brown      Blue     Hazel     Green 
## 0.3716216 0.3631757 0.1570946 0.1081081

条件付確率(目の色が青い時の、髪の毛が黒い確率)

EyeHairProp["Blue",]/eyeProp["Blue"]

##      Black      Brown        Red      Blond 
## 0.09302326 0.39069767 0.07906977 0.43720930