列聯表、卡方檢定 (Contingency table、Chi-Square test) 【一】

SAS Codes：

/*將資料讀進SAS*/

data Color;
/*$代表變數為文字  @@為自由符號使不同的觀測值可以放在同一行，如範例*/

   input Region Eyes $ Hair $ Count @@;

/*更改變數的lable*/

   label Eyes  ='Eye Color'

         Hair  ='Hair Color'

         Region='Geographic Region';

   datalines;

1 blue  fair   23  1 blue  red     7  1 blue  medium 24

1 blue  dark   11  1 green fair   19  1 green red     7

1 green medium 18  1 green dark   14  1 brown fair   34

1 brown red     5  1 brown medium 41  1 brown dark   40

1 brown black   3  2 blue  fair   46  2 blue  red    21

2 blue  medium 44  2 blue  dark   40  2 blue  black   6

2 green fair   50  2 green red    31  2 green medium 37

2 green dark   23  2 brown fair   56  2 brown red    42

2 brown medium 53  2 brown dark   54  2 brown black  13

;
/*印出前5筆資料*/

proc print data=Color  (obs=5); run;

/*
若無加權數(weight)跑Eyes與Eyes*Hair的列聯表
加入chisq語法可以做卡方檢定
此例子的虛無假設(H0)為不同顏色頭髮的比例相同<=>P1=P2=P3

*/

proc freq data=Color;

   tables Eyes  Eyes*Hair / out=FreqCount outexpect sparse   chisq ;

   title 'Eye and Hair Color of European Children without weight' ;

run;

/*加權數(weight)跑Eyes與Eyes*Hair的列聯表*/

proc freq data=Color;

   tables Eyes  Eyes*Hair / out=FreqCount outexpect sparse   chisq ;

   weight Count;

   title 'Eye and Hair Color of European Children with weight';

run;

proc print data=FreqCount noobs;

   title2 'Output Data Set from PROC FREQ';

run;

資料來源：
SAS Help and documentation Example 36.1 Output Data Set of Frequencies