[R] impenetrable warning

[Liaw, Andy]

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
> 
>