/*---------------------------------------------------*/ 

   /*                                                                */ 

   /*               Behavior of Squirrel Monkeys                     */ 

   /*               ----------------------------                     */ 

   /* In a population of 6 squirrel monkeys, the joint distribution  */ 

   /* of genital display with respect to (active role, passive role) */ 

   /* was observed. Since a monkey cannot have both the active and   */ 

   /* passive roles in the same interaction, the diagonal cells of   */ 

   /* the table are structural zeros.                                */ 

   /*                                                                */ 

   /* From: Fienberg (1980, Table 8-2)                               */ 

   /*                                                                */ 

   /* Illustrate: log-linear model, structural zeros and random      */ 

   /*             zeros                                              */ 

   /*                                                                */ 

   /*----------------------------------------------------------------*/ 

     title 'BEHAVIOR OF SQUIRREL MONKEYS'; 

     data display; 

        input active $ passive $ wt @@; 

        if active ne 't'; 

        if active ne passive then if wt=0 then wt=1e-20; 

        cards; 

     r r  0    r s  1    r t  5    r u  8    r v  9    r w  0 

     s r 29    s s  0    s t 14    s u 46    s v  4    s w  0 

     t r  0    t s  0    t t  0    t u  0    t v  0    t w  0 

     u r  2    u s  3    u t  1    u u  0    u v 38    u w  2 

     v r  0    v s  0    v t  0    v u  0    v v  0    v w  1 

     w r  9    w s 25    w t  4    w u  6    w v 13    w w  0 

     ; 

     proc catmod; 

        weight wt; 

        model active*passive=_response_ 

            / ml nogls freq pred=freq noparm noresponse; 

        loglin active passive; 

        title2 'TEST QUASI-INDEPENDENCE FOR THE INCOMPLETE TABLE'; 

     run;