Programming the statistical procedures from SAS

Proc genmod algorithm converged, but iteration limit exceeded

Occasional Learner
Posts: 1

Proc genmod algorithm converged, but iteration limit exceeded

[ Edited ]

I'm analyzing roughly 300 subjects with 36 clusters. Both my explanatory and dependent variable are continuously distributed. I'm using proc genmod to adjust for the repeated measurements within the clusters. In my baseline model of this association, I see that the algorithm converged but also a note/warning about convergence. I get parameter estimate and they are within my expectation so there doesn't seem to be anything unbelievably wrong with the results, but the warning still concerns me. 



proc genmod data=data;
  class   cluster;
  model outcome = average_score / dist=normal link=identity;
  repeated subject=cluster / type=cs;

NOTE: Algorithm converged.
NOTE: No convergence of GEE parameter estimates after 50 iterations.
WARNING: Iteration limit exceeded. 


After running this base model I add covariates in and have no issues with convergence or iterations. There are then two "NOTE: Algorithm converged." lines in my log. This is contrary to what I would think since I'm adding more parameters to the model to estimate. 


I also have run some sensitivity analyses using a weighted average score and that model (with and without covariates) has no convergence issues. 


Any ideas whats up with this?

Super User
Posts: 10,046

Re: Proc genmod algorithm converged, but iteration limit exceeded

Make the number of iterative bigger ?


proc genmod data=sashelp.class;
  class   sex;
  model weight = height / dist=normal link=identity maxiter=100;
  repeated subject=sex / type=cs;
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