[R] trouble with nlme: Error in MEEM() : Singularity in backsolve at level 0, block 1

[Uwe Ligges]

On 06.10.2013 03:11, Robert Lynch wrote:
> I am trying to fit my data, attached,  with the following model
>
> CutOff <- 0
>
> fit.full <- lme(fixed= zGrade ~ Rep + ISE +Yfrm7A +Ufrm7A +Female +White
> +HSGPA +MATH +AP_TOTAL +Years +Course +
>                   Course*Rep + Course*ISE +Course*Yfrm7A+Course*Ufrm7A
> +Course*Female +Course*White +Course*HSGPA +Course*MATH +Course*AP_TOTA
> L+Course*Years,
>                  random= ~1|SID,
>                  data = Master.complete[Master.complete$GRADE >= CutOff,])
>   I get the following error
> Error in MEEM(object, conLin, control$niterEM) :
>    Singularity in backsolve at level 0, block 1
>
>
> when I take out
> +Course*Yfrm7A+Course*Ufrm7A
> and just use
> fit.full <- lme(fixed= zGrade ~ Rep + ISE +Yfrm7A +Ufrm7A +Female +White
> +HSGPA +MATH +AP_TOTAL +Years +Course +
>                   Course*Rep + Course*ISE
> +Course*Female+Course*White+Course*HSGPA+Course*MATH+Course*AP_TOTAL+Course*Years,
>                  random= ~1|SID,
>                  data = Master.complete[Master.complete$GRADE >= CutOff,])
>    I don't get an error
>
> I think this is because when Course == P7A  Yfrm7A==Ufrm7A==0.

Hmmmm, actually it does not make sense to include constant variables in 
your model. Please talk to your supervisor, this i not a problem with R 
but about understanding the model.

Best,
Uwe Ligges


 > I am not
> sure how to work around this.  any suggestions would be welcome.
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>