lme convergence

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lme convergence

Ashraf Chaudhary
Dear All:

 

lme(sbp ~ cengirth, data = family, random= ~ 1 | familyid)

 

converges but

 

lme(sbp ~ cengirth, data = family, random= ~ cengirth | familyid)

 

does not.

 

I get the following message:

 

Error in lme.formula(sbp ~ cengirth, data = family, random = ~cengirth |
:

        iteration limit reached without convergence (9)

 

The data has 488 rows and 154 familyid levels. For some familyid levels,
there is only one row and cengirth is 0 as it is a centered variable
within familyid.

 

I appreciate your pointing me to the source of the problem.

 

Ashraf

_________________________________
M. Ashraf Chaudhary, Ph.D.
Department of International Health
Johns Hopkins Bloomberg School of Public Health
615 N. Wolfe St.  Room W5506
Baltimore MD 21205-2179

(410) 502-0741/fax: (410) 502-6733
[hidden email] <mailto:[hidden email]>

 


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Re: lme convergence

Spencer Graves
Dear Dr. Chaudhary:

          Because your example is not self contained (i.e., your data.frame
"family" is not something distributed with R), I can only guess.

          Have you tried things like the following:

          with(family, table(cengirth, familyid))

          If each level of familyid is associated with only one level of
cengirth, then it's clear that your data cannot support the estimation
of a random perturbation to the slope of the line for "cengirth"
associated with each level of familyid.  If you have only a very few
such linkages, I suggest you increase the iteration limit and try again;
  the lme documentation will tell you how to do that.

          Also, have you read Pinheiro and Bates (2000) Mixed-Effects Models in
S and S-Plus?  I've learned some extremely valuable things from Doug
Bates, including from the contents of this book, and I highly recommend
it.

          If it were my problem and I'd done more or less all of the above
without getting an answer to my question, I might start looking for a
simpler example that would still replicate the error.  If I could have
copied a few lines of code out of your email, pasted them into R and
replicated your error, I almost certainly could have given a more
precise diagnosis.  If you get a simple example that you still don't
understand and would like further help from this group, PLEASE do read
the posting guide! "www.R-project.org/posting-guide.html" and submit a
follow-on question describing this simple example and what you don't
understand about it.

          hope this helps.
          spencer graves

Chaudhary, Mohammad A. wrote:

> Dear All:
>
>  
>
> lme(sbp ~ cengirth, data = family, random= ~ 1 | familyid)
>
>  
>
> converges but
>
>  
>
> lme(sbp ~ cengirth, data = family, random= ~ cengirth | familyid)
>
>  
>
> does not.
>
>  
>
> I get the following message:
>
>  
>
> Error in lme.formula(sbp ~ cengirth, data = family, random = ~cengirth |
> :
>
>         iteration limit reached without convergence (9)
>
>  
>
> The data has 488 rows and 154 familyid levels. For some familyid levels,
> there is only one row and cengirth is 0 as it is a centered variable
> within familyid.
>
>  
>
> I appreciate your pointing me to the source of the problem.
>
>  
>
> Ashraf
>
> _________________________________
> M. Ashraf Chaudhary, Ph.D.
> Department of International Health
> Johns Hopkins Bloomberg School of Public Health
> 615 N. Wolfe St.  Room W5506
> Baltimore MD 21205-2179
>
> (410) 502-0741/fax: (410) 502-6733
> [hidden email] <mailto:[hidden email]>
>
>  
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

______________________________________________
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