R help - May 2009 - Extracting correlation in a nlme model

Hi R users:

Is there a function to obtain the correlation within groups
from this very simple lme model?
> modeloMx1
Linear mixed-effects model fit by REML
  Data: barrag 
  Log-restricted-likelihood: -70.92739
  Fixed: fza_tension ~ 1 
(Intercept) 
   90.86667 

Random effects:
 Formula: ~1 | molde
        (Intercept) Residual
StdDev:    2.610052 2.412176

Number of Observations: 30
Number of Groups: 3 

I want to obtain \rho = \sigma_b^2 / (\sigma_b^2 + \sigma^2)

I know that I obtain \sigma_b^2 and \sigma^2 with
> VarCorr(modeloMx1)
molde = pdLogChol(1) 
            Variance StdDev  
(Intercept) 6.812374 2.610052
Residual    5.818593 2.412176

But, I want to know if I can obtain
\rho = 6.8123/(6.8123 + 5.8185) = 0.53934 straightforward.

Thank you for you help.

Kenneth

Hello,

for calculation of intraclass correlation coefficient for a simple Random
Intercept model, the function ICC1.lme() in the package "psychometric"
can
be applied.

Best regards, 
Christine Adrion






Kenneth Roy Cabrera Torres wrote:
> 
> Hi R users:
> 
> Is there a function to obtain the correlation within groups
> from this very simple lme model?
> 
>> modeloMx1
> Linear mixed-effects model fit by REML
>   Data: barrag 
>   Log-restricted-likelihood: -70.92739
>   Fixed: fza_tension ~ 1 
> (Intercept) 
>    90.86667 
> 
> Random effects:
>  Formula: ~1 | molde
>         (Intercept) Residual
> StdDev:    2.610052 2.412176
> 
> Number of Observations: 30
> Number of Groups: 3 
> 
> I want to obtain \rho = \sigma_b^2 / (\sigma_b^2 + \sigma^2)
> 
> I know that I obtain \sigma_b^2 and \sigma^2 with
> 
>> VarCorr(modeloMx1)
> 
> molde = pdLogChol(1) 
>             Variance StdDev  
> (Intercept) 6.812374 2.610052
> Residual    5.818593 2.412176
> 
> But, I want to know if I can obtain
> \rho = 6.8123/(6.8123 + 5.8185) = 0.53934 straightforward.
> 
> Thank you for you help.
> 
> Kenneth
> 
> ______________________________________________
> R-help@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.
> 
> 

-----
Christine Adrion, Dipl.-Stat., MPH
 
Ludwig-Maximilians-Universitaet Muenchen
IBE – Institut für Medizinische Informations-
verarbeitung, Biometrie und Epidemiologie 
Marchioninistr. 15
81377 Muenchen
GERMANY
 
Tel.:      +49 (0)89 7095-4483
eMail:     adrion@ibe.med.uni-muenchen.de  
Internet: http://ibe.web.med.uni-muenchen.de
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