Infinite Likelihood error Proc Mixed

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Occasional Contributor vvk
Occasional Contributor
Posts: 6

Infinite Likelihood error Proc Mixed

Hi All,

I am using proc mixed model, and i got the following warning.

WARNING: Stopped because of infinite likelihood.

WARNING: Output 'lsmeans' was not created.  Make sure that the output object name, label, or path

         is spelled correctly.  Also, verify that the appropriate procedure options are used to

         produce the requested output object.  For example, verify that the NOPRINT option is not

         used.

The model is working fine with individual visit data but when I run the model with all the visits it failed.

No duplicate records, no missing data. The same model worked for even lesser population.

Model Used:

     proc mixed data=dsnin;

  

    class treatment visit subjid ;

    model pchg =  treatment visit treatment *visit base/solution ddfm=satterthwaite;

    repeated visit/subject=subjid type=un;

    lsmeans treatment *visit/cl alpha=0.05;

    ods output lsmeans=means;

    run;

Any kind of help is greatly appreciated.

Thank you.

Respected Advisor
Posts: 2,655

Re: Infinite Likelihood error Proc Mixed

Almost certainly the infinte likelihood is due to duplicate records.  For each subjid, there can be only one record per "visit".  If the subjid is not unique within treatment, then this error will occur.  If that is the case, then change subject=subjid to subject=subjid*treatment, and all should be well.  Otherwise, you are going to have clean your data so that there are no duplicate records for visit.

Steve Denham

Occasional Contributor vvk
Occasional Contributor
Posts: 6

Re: Infinite Likelihood error Proc Mixed

Thanks Steve for your response. I will try that and check if it works.

New Contributor
Posts: 2

Re: Infinite Likelihood error Proc Mixed

Hi Steve,

I have a question about error source in split-split plot design. I have combined two years of data as follows;

class Year Rep Irrig Tillage Variety;

model HJul24 =  Irrig|Tillage|Variety;

Random  Rep(Year) Rep(Year Irrig)  Rep(Year Irrig Tillage);

Irrig was the main plot, Tillage was the subplot, and Variety was the sub-subplot in three replicates. I would like to consider year in the random model. My question is; should I include the Tillage in the random model or not. As I will say in the paper;

Irrigation, tillage, variety, and their interaction were considered as fixed effects. Year, replicate, and their interaction with irrigation and tillage were considered as random effects.


Thank you very much.


Ahmed Attia

Respected Advisor
Posts: 2,655

Re: Infinite Likelihood error Proc Mixed

Hi Ahmed,

If you have sufficient data to estimate the variance components with tillage included, I would put them into the random statement.  However, I would be very surprised if the message "G matrix is not postive definite" or some such does not appear.  The reason for still including them is that they are part of the design, and the degrees of freedom for tests should reflect the "skeleton ANOVA" (see Stroup's Generalized Linear Mixed Models for more on this).

Steve Denham

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