[R] Extract random effect variances from lmer (lme4) model

[Ista Zahn]

Perhaps

as.data.frame(VarCorr(pcrpred))

?

Best,
Ista

On Mon, Dec 8, 2014 at 4:15 PM, GMAIL <rosita21 at gmail.com> wrote:
> I have a mer object that has fixed and random effects (lmer).
>
> How do I extract the variance or standard deviation estimates for the random and fixed effects? Here is a simplified version of my question:
>
>
> pcrpred <- lmer(PCR ~ (1|TIME) + (1|ID), data = mydataPCRlong)
>
> pcrpred
>
>
> This gives a long output - not too long in this case. Anyway, how do I explicitly select the variance? I can I extract part of the output? I want the values themselves.
>
>> pcrpred
> Linear mixed model fit by REML ['merModLmerTest']
> Formula: PCR ~ (1 | TIME) + (1 | ID)
>    Data: mydataPCRlong
> REML criterion at convergence: 127761.9
> Random effects:
>  Groups   Name        Std.Dev.
>  ID       (Intercept) 22031
>  TIME     (Intercept) 15182
>  Residual             33635
> Number of obs: 5346, groups:  ID, 891; TIME, 6
> Fixed Effects:
> (Intercept)
>       26791
>
> I also tried:
> summary(pcrpred)
>
> Linear mixed model fit by REML t-tests use Satterthwaite approximations to degrees of
>   freedom [merModLmerTest]
> Formula: PCR ~ (1 | TIME) + (1 | ID)
>    Data: mydataPCRlong
>
> REML criterion at convergence: 127761.9
>
> Scaled residuals:
>     Min      1Q  Median      3Q     Max
> -2.6822 -0.5974 -0.2283  0.5681  2.8165
>
> Random effects:
>  Groups   Name        Variance  Std.Dev.
>  ID       (Intercept) 4.854e+08 22031
>  TIME     (Intercept) 2.305e+08 15182
>  Residual             1.131e+09 33635
> Number of obs: 5346, groups:  ID, 891; TIME, 6
>
> Fixed effects:
>              Estimate Std. Error        df t value Pr(>|t|)
> (Intercept) 26790.662   6258.611     5.142   4.281  0.00738 **
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>> print(VarCorr(pcrpred),comp=c("Variance","Std.Dev."))
>  Groups   Name        Variance   Std.Dev.
>  ID       (Intercept)  485373501 22031
>  TIME     (Intercept)  230483110 15182
>  Residual             1131284840 33635
>
>
> When I do:
>
> print(VarCorr(pcrpred),comp=c(“Variance”,”Std.Dev.”))
>
> I get:
>
>  Groups   Name        Variance   Std.Dev.
>  ID       (Intercept)  485373501 22031
>  TIME     (Intercept)  230483110 15182
>  Residual             1131284840 33635
>
> And I searched in forums, but another command I found was:
> summary(pcrpred)@REmat
> however I get:
>
> Error: trying to get slot “REmat" from an object (class "summary.merMod") that is not an S4 object
>
> Can anyone
>
>
> I have taken long looks at
>
> str(study)
> and there's nothing there! Also checked any extractor functions in the lme4 package to no avail. Please help!
>         [[alternative HTML version deleted]]
>
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