[R] impenetrable warning

[Spencer Graves]

      In this case, this trick will identify the specify command in the 
lme code that produce the error. 

      If that does not lead you to an answer, have you tried simplifying 
your lme call to identify more clearly which part (or combination) seems 
to generate the problem? 

      hope this helps.  spencer graves

Liaw, Andy wrote:

>Generally you can set options(warn=2), run the code, then do traceback().
>
>Andy
>
>  
>
>>From: Simon.Bond
>>
>>Dear R-help,
>>
>>Can anyone explain the meaning of  the warning,
>>
>>Singular precision matrix in level -1, block 1
>>
>>? Or how to track down where it comes from?
>>
>>More precisely, using the nlme package, I'm issued with the warning
>>
>>itt2 <- lme(lrna~rx.nrti+lbrna, random=~1|patid,
>>cor=corExp(form=~days|patid,nugget=T), weights=varPower(
>>form=~lbrna),data=rna3)
>>Warning messages:
>>1: Singular precision matrix in level -1, block 1
>>2: Singular precision matrix in level -1, block 1
>>
>>the output is:
>>
>>Linear mixed-effects model fit by REML
>>  Data: rna3
>>  Log-restricted-likelihood: -4990.142
>>  Fixed: lrna ~ rx.nrti + lbrna
>>   (Intercept) rx.nrtiZDV+3TC rx.nrtiZDV+ABC          lbrna
>>     2.6597552      0.8589514      0.4259504      0.2929222
>>
>>Random effects:
>> Formula: ~1 | patid
>>        (Intercept)  Residual
>>StdDev:    1.251113 0.2105329
>>
>>Correlation Structure: Exponential spatial correlation
>> Formula: ~days | patid
>> Parameter estimate(s):
>>      range      nugget
>>204.6422150   0.3349336
>>Variance function:
>> Structure: Power of variance covariate
>> Formula: ~lbrna
>> Parameter estimates:
>>    power
>>0.9733358
>>Number of Observations: 2390
>>Number of Groups: 124
>>
>>
>>
>>Thanks,
>>
>>Simon Bond.
>>
>>______________________________________________
>>R-help at stat.math.ethz.ch mailing list
>>https://stat.ethz.ch/mailman/listinfo/r-help
>>PLEASE do read the posting guide! 
>>http://www.R-project.org/posting-guide.html
>>
>>
>>    
>>
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
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>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>  
>

-- 
Spencer Graves, PhD, Senior Development Engineer
O:  (408)938-4420;  mobile:  (408)655-4567