Dear R-mixed-model-experts:

I am running R version 2.12.1 on Windows 2007. I am studying environmental
factors and maternal behavior in the body condition of sea lion pups from
California.

I specified my model as follows:

Model <- lmer
(Condicion~DuracionNurse+FrecNurse+FrecInteraccion+Temperatura+Densidad+(1|Mes)+(1|Zona)+(1|Sexo)+(1|Marea)+(1|Temporada),
family=gaussian, data=Datos)

(See output below)

At this point, my main questions are:

1. Is my model correctly built?

2. Why don’t I get p values for t?

3. Is there any way to compute p values for the fixed effects?


Linear mixed model fit by REML
Formula: Condicion ~ DuracionNurse + FrecNurse + FrecInteraccion +
Temperatura +      Densidad + (1 | Mes) + (1 | Zona) + (1 | Sexo) + (1
| Marea) +      (1 | Temporada)
   Data: Datos
   AIC   BIC logLik deviance REMLdev
 646.6 682.5 -311.3    619.1   622.6
Random effects:
 Groups    Name        Variance   Std.Dev.
 Mes       (Intercept) 2.8159e-01 5.3065e-01
 Marea     (Intercept) 2.1107e-01 4.5943e-01
 Zona      (Intercept) 2.1056e-01 4.5886e-01
 Temporada (Intercept) 1.4041e-01 3.7472e-01
 Sexo      (Intercept) 6.9748e-11 8.3515e-06
 Residual              3.8768e+00 1.9690e+00
Number of obs: 147, groups: Mes, 4; Marea, 3; Zona, 3; Temporada, 2; Sexo, 2

Fixed effects:
                 Estimate Std. Error t value
(Intercept)      69.01515   17.74172   3.890
DuracionNurse     0.04564    0.27483   0.166
FrecNurse         3.00491    0.79289   3.790
FrecInteraccion  -0.62826    0.17585  -3.573
Temperatura      -2.87229    0.91138  -3.152
Densidad        -18.78045    6.22638  -3.016

Correlation of Fixed Effects: (Intr) DrcnNr FrcNrs FrcInt Tmprtr
DuracionNrs 0.741 FrecNurse 0.945 0.582 FrecIntrccn -0.965 -0.691 -0.977
Temperatura -0.999 -0.741 -0.954 0.972 Densidad -0.919 -0.878 -0.823 0.862
0.915

I appreciate very much in advance for your help and I hope your answer.
Best Regards..

Karina


-- 
Biol. Karina Villegas Cervantes
Estudiante de Maestría PCMyL - UNAM

Laboratorio de Ecologia de Pinnipedos Burney J. Le Boueuf.
CICIMAR-IPN
Av. Instituto Politecnico Nacional s/n.Col.Playa Palo de Santa Rita
La Paz Baja California Sur, Mexico.

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