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summary(cars)
##      speed           dist       
##  Min.   : 4.0   Min.   :  2.00  
##  1st Qu.:12.0   1st Qu.: 26.00  
##  Median :15.0   Median : 36.00  
##  Mean   :15.4   Mean   : 42.98  
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library(vcd)
## Loading required package: grid
View(Arthritis)
mytable <- xtabs(~ Treatment + Sex + Improved, data= Arthritis)
mytable
## , , Improved = None
## 
##          Sex
## Treatment Female Male
##   Placebo     19   10
##   Treated      6    7
## 
## , , Improved = Some
## 
##          Sex
## Treatment Female Male
##   Placebo      7    0
##   Treated      5    2
## 
## , , Improved = Marked
## 
##          Sex
## Treatment Female Male
##   Placebo      6    1
##   Treated     16    5
mytable <- xtabs(~ Treatment + Sex+ Improved, data = Arthritis)
ftable(mytable)
##                  Improved None Some Marked
## Treatment Sex                             
## Placebo   Female            19    7      6
##           Male              10    0      1
## Treated   Female             6    5     16
##           Male               7    2      5
margin.table(mytable,1)
## Treatment
## Placebo Treated 
##      43      41
margin.table(mytable,2)
## Sex
## Female   Male 
##     59     25
margin.table(mytable,3)
## Improved
##   None   Some Marked 
##     42     14     28
margin.table(mytable,c(1,3))
##          Improved
## Treatment None Some Marked
##   Placebo   29    7      7
##   Treated   13    7     21
margin.table(mytable,c(2,3))
##         Improved
## Sex      None Some Marked
##   Female   25   12     22
##   Male     17    2      6
ftable(prop.table(mytable,c(1,2)))
##                  Improved       None       Some     Marked
## Treatment Sex                                             
## Placebo   Female          0.59375000 0.21875000 0.18750000
##           Male            0.90909091 0.00000000 0.09090909
## Treated   Female          0.22222222 0.18518519 0.59259259
##           Male            0.50000000 0.14285714 0.35714286
ftable(prop.table(mytable))
##                  Improved       None       Some     Marked
## Treatment Sex                                             
## Placebo   Female          0.22619048 0.08333333 0.07142857
##           Male            0.11904762 0.00000000 0.01190476
## Treated   Female          0.07142857 0.05952381 0.19047619
##           Male            0.08333333 0.02380952 0.05952381