[R-sig-ME] p values absent in lmer output

[Luciano La Sala]

Dear R-mixed-models experts, 

I am running R version 2.8.1 on Windows Vista. I am studying factors which influence egg morphometrics in a seagull population. My dataset consists of: “Year” (0,1), “HatchingOrder” (HO) (1, 2, 3) and “ClutchSize” (1, 2, 3) as independent variables, and “Egg measurements” (I run models for max. breadth, length and volume) as dependent variable (continuous). I included “NestID” as a random effect. 

I specified my model as follows: 

model <- lmer(EggVolume~HO+Year+ClutchSize+(1|NestID),Data)
summary(model)

(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. If I simplify my model to: lmer (EggVolume ~ HO+ (1|NestID), Data) 
.... I still don't get any p values. How is that possible? Is there any way to compute p values for the fixed effects? 

Linear mixed model fit by REML 
Formula: EggVol ~ HatchingOrder1 + EggVol + Year1 + ClutchSize + (1 | NestID) 
Data: Data 

AIC     BIC     logLik     deviance     REMLdev
1441    1469    -712.3     1431         1425

Random effects:
Groups     Name              Variance     Std.Dev.
NestID     (Intercept)       21.9883      4.6892  
Residual                      7.9196      2.8142  

Number of obs: 248, groups: NestID, 120

Fixed effects:
                       Estimate          Std. Error          t value
(Intercept)            77.060             1.124              68.54
HatchingOrder1Second   -2.227             0.443              -5.03
HatchingOrder1Third    -5.945             0.544              -10.93
Year2006               -2.504             0.969              -2.58
ClutchSizeTwo-eggs      2.101             1.349               1.56
ClutchSizeThree-eggs    5.869             1.243               4.72

Correlation of Fixed Effects:
               (Intr)     HtcO1S     HtcO1T    Y12006    CltchSzTw-
HtchngOrd1S   -0.004                                
HtchngOrd1T   -0.018      0.407                         
Year12006     -0.460      0.008      0.038                  
CltchSzTw-g   -0.598     -0.153      -0.067    -0.129          
CltchSzThr-   -0.734     -0.177      -0.216     0.046    0.616  
   
Thank you very much in advance! 

Luciano 



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