title: Root mean square error in R - mixed effect model
body: <p>Could you please tell me how to get/compute the value RMSE (root mean square error) in R when you perform a mixed effect model</p>
  
  <pre><code>Data: na.omit(binh) 
         AIC      BIC    logLik
    888.6144 915.1201 -436.3072
  
  Random effects:
   Formula: ~1 | Study
          (Intercept) Residual
  StdDev:    3.304345 1.361858
  
  Fixed effects: Eeff ~ ADF + CP + DE + ADF2 + DE2 
                  Value Std.Error  DF   t-value p-value
  (Intercept)  -0.66390 18.870908 158 -0.035181  0.9720
  ADF           1.16693  0.424561 158  2.748556  0.0067
  CP            0.25723  0.097524 158  2.637575  0.0092
  DE          -36.09593 12.031791 158 -3.000046  0.0031
  ADF2         -0.03708  0.011014 158 -3.366625  0.0010
  DE2           4.77918  1.932924 158  2.472513  0.0145
   Correlation: 
       (Intr) ADF    CP     DE     ADF2  
  ADF  -0.107                            
  CP   -0.032  0.070                     
  DE    0.978 -0.291 -0.043              
  ADF2  0.058 -0.982 -0.045  0.250       
  DE2  -0.978  0.308  0.039 -0.997 -0.265
  
  Standardized Within-Group Residuals:
          Min          Q1         Med          Q3         Max 
  -2.28168116 -0.45260885  0.06528363  0.57071734  2.54144168 
  
  Number of Observations: 209
  Number of Groups: 46 
  </code></pre>