/* Fit a linear logistic model with a clinic-specific effect to a 
   data set from a multi-center clinical trial.
   (3) Using a marginal approack (i.e. GEE)
*/
options ls=80 center pagesize=60 number label;

data clin;
  input clinic trt $ fav unfav ;
  nij=fav+unfav;
  datalines;
1 drug 11 25
1 cntl 10 27
2 drug 16  4
2 cntl 22 10
3 drug 14  5
3 cntl  7 12
4 drug  2 14
4 cntl  1 16
5 drug  6 11
5 cntl  0 12
6 drug  1 10
6 cntl  0 10
7 drug  1  4
7 cntl  1  8 
8 drug  4  2
8 cntl  6  1 
;

proc genmod;
  class clinic trt;
  model fav/nij = trt / dist=bin link=logit;
  repeated subject=clinic / type=ind;
  title 'GEE: using a working independence model';

proc genmod;
  class clinic trt;
  model fav/nij = trt / dist=bin link=logit;
  repeated subject=clinic / type=cs;
  title 'GEE: using a working CS model';

proc genmod;
  class clinic trt;
  model fav/nij = trt / dist=bin link=logit;
  repeated subject=clinic / type=un;
  title 'GEE: using a working unstructured model';

/* default maxit=50 */
proc genmod;
  class clinic trt;
  model fav/nij = trt / dist=bin link=logit;
  repeated subject=clinic / type=cs maxit=500;
  title 'GEE: using MORE ITERATIONS and a working CS model';
run;
******************
                    GEE: using a working independence model                    1

          Criterion                 DF           Value        Value/DF

          Deviance                  14         90.9602          6.4972
          Scaled Deviance           14         90.9602          6.4972
          Pearson Chi-Square        14         81.5126          5.8223
          Scaled Pearson X2         14         81.5126          5.8223
          Log Likelihood                     -179.1170                

                    Analysis Of Initial Parameter Estimates
 
                               Standard       Wald 95%          Chi-
Parameter        DF  Estimate     Error   Confidence Limits   Square  Pr > ChiSq

Intercept         1   -0.3102    0.1775   -0.6581    0.0378     3.05      0.0806
trt        cntl   1   -0.4040    0.2514   -0.8968    0.0887     2.58      0.1080
trt        drug   0    0.0000    0.0000    0.0000    0.0000      .         .    
Scale             0    1.0000    0.0000    1.0000    1.0000                     

                      Analysis Of GEE Parameter Estimates
                      Empirical Standard Error Estimates
 
                              Standard   95% Confidence
      Parameter      Estimate    Error       Limits            Z Pr > |Z|

      Intercept       -0.3102   0.3875  -1.0696   0.4493   -0.80   0.4235
      trt       cntl  -0.4040   0.2462  -0.8866   0.0785   -1.64   0.1008
      trt       drug   0.0000   0.0000   0.0000   0.0000     .      .    


                         GEE: using a working CS model                         3

  WARNING: Iteration limit exceeded.                                         

                      Analysis Of GEE Parameter Estimates
                      Empirical Standard Error Estimates
 
                              Standard   95% Confidence
      Parameter      Estimate    Error       Limits            Z Pr > |Z|

      Intercept        1.9203   1.7200  -1.4508   5.2914    1.12   0.2642
      trt       cntl  -0.5823   0.6913  -1.9371   0.7725   -0.84   0.3996
      trt       drug   0.0000   0.0000   0.0000   0.0000     .      .    

                    GEE: using a working unstructured model                    5

  WARNING: Iteration limit exceeded.                                         

                      Analysis Of GEE Parameter Estimates
                      Empirical Standard Error Estimates
 
                              Standard   95% Confidence
      Parameter      Estimate    Error       Limits            Z Pr > |Z|

      Intercept        1.9203   1.7200  -1.4508   5.2914    1.12   0.2642
      trt       cntl  -0.5823   0.6913  -1.9371   0.7725   -0.84   0.3996
      trt       drug   0.0000   0.0000   0.0000   0.0000     .      .    

               GEE: using MORE ITERATIONS and a working CS model

  WARNING: Iteration limit exceeded.

                      Analysis Of GEE Parameter Estimates
                      Empirical Standard Error Estimates

                              Standard   95% Confidence
      Parameter      Estimate    Error       Limits            Z Pr > |Z|

      Intercept        1.9203   1.7200  -1.4508   5.2914    1.12   0.2642
      trt       cntl  -0.5823   0.6913  -1.9371   0.7725   -0.84   0.3996
      trt       drug   0.0000   0.0000   0.0000   0.0000     .      .