R语言实战 - 基本统计分析（2）- 频数表和列联表

数据：

> library(vcd)
> head(Arthritis)
  ID Treatment  Sex Age Improved
1 57   Treated Male  27     Some
2 46   Treated Male  29     None
3 77   Treated Male  30     None
4 17   Treated Male  32   Marked
5 36   Treated Male  46   Marked
6 23   Treated Male  58   Marked
> 

1. 生成频数表

1.1 一维列联表

> mytable <- with(Arthritis, table(Improved))
> mytable
Improved
  None   Some Marked 
    42     14     28 
> prop.table(mytable)
Improved
     None      Some    Marked 
0.5000000 0.1666667 0.3333333 
> prop.table(mytable)*100
Improved
    None     Some   Marked 
50.00000 16.66667 33.33333 
> 

1.2 二维列联表