/* Example 3 */
     data lung_cancer;
      input cancer $ wife_smoker $ count;
      datalines;
   Yes     Yes    2 
   Yes      No    6
   No      Yes   26 
   No       No  154
   ; 
   proc freq order=data;        
      weight count;
      tables cancer*wife_smoker / chisq nocol;
   run; 

   proc freq order=data;
      weight count;
      tables cancer*wife_smoker / chisq nocol;
      exact chisq;
   run;