Dear R-people: 

 

I have run a GLMM (using lmer) with the fixed and random effects detailed
below. Oddly I think, I get zero variance and Std. Dev. values. 

How is that possible? Does it mean that the RE "NestID" is not helping to
account for autocorrelation among sibling chicks at the nest level? 

Or is this a small sample size problem? 

 

As well, I ran an ordinary logistic regression using he exact same fixed
variables, and I got the exact same AIC and BIC values and estimates for
fixed effects, error, z value, and Pr(>|z|). 

 

Does this support the idea that the GLMM with RE for NestID is not necessary
at all? 

 

Look forward to hearing from you. 

Cheers for now.

 

Luciano   

 

 

GENERALIZED LINEAR MIXED MODEL WITH RANDOM INTERCEPT

 

model <- lmer(Death10~HO+ClutchSize+SibComp+Yr+(1|NestID),family=binomial,1)

 

Generalized linear mixed model fit by the Laplace approximation 

Formula: Death10 ~ HO + ClutchSize + Sibcomp + yr + (1 | NestID) 

 

Data: 1 

AIC      BIC       logLik     deviance

242.2    268.5     -113.1     226.2

 

Random effects:

Groups Name           Variance      Std. Dev.

NestID (Intercept)    0                  0      

 

Number of obs: 198, groups: NestID, 104

 

Fixed effects:

                                   Estimate                     Std. Error
z value             Pr(>|z|)  

(Intercept)                   -1.2239                      0.5114
-2.3934           0.0167 *

HOSecond                  -0.6910                      0.8928
-0.7739           0.4390  

HOThird                       0.6768                       1.0327
0.6554             0.5122  

ClutchSizeTwo-eggs     1.3961                     0.5864             2.3809
0.0173 *

ClutchSizeThree-eggs   0.3958                      0.5843             0.6773
0.4982  

SibcompAbsent             1.7804                     0.9140
1.9479             0.0514 .

yr2007                         -0.8299                      0.3423
-2.4245           0.0153 *

---

 

Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 

 

 

Correlation of Fixed Effects:

                          (Intr)      HOScnd     HOThrd     CltchSzTw-
CltchSzTh-   SbcmpA

HOSecond        -0.034                                            

HOThird           -0.031    0.837                                    

CltchSzTw-g   -0.830   -0.069          -0.022                             

CltchSzThr-      -0.816   -0.088          -0.107         0.785


SibcmpAbsnt     0.052   -0.904          -0.836       -0.018
-0.050           

yr2007              -0.233    0.145           0.133         0.025
-0.050       - 0.224

 

 


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