Hello,
   
  I am a bit confused about gamm in mgcv. Consulting Wood (2006) or Ruppert et al. (2003) hasn't taken away my confusion.
   
  In this code from the gamm help file:
   
     b2<-gamm(y~s(x0)+s(x1)+s(x2)+s(x3),family=poisson,random=list(fac=~1))

  Am I correct in assuming that we have a random intercept here....but that the amount of smoothing is also changing per level of the factor?? Or is it only the intercept that is changing?
   
   
  And where can I find some explanation on the magic output below?
   
  Thanks
  Piet
   
   
  summary(b2$lme)
  Random effects:
 Formula: ~Xr.1 - 1 | g.1
 Structure: pdIdnot
           Xr.11    Xr.12    Xr.13    Xr.14    Xr.15    Xr.16    Xr.17    Xr.18
StdDev: 1.680679 1.680679 1.680679 1.680679 1.680679 1.680679 1.680679 1.680679
   Formula: ~Xr.2 - 1 | g.2 %in% g.1
 Structure: pdIdnot
          Xr.21   Xr.22   Xr.23   Xr.24   Xr.25   Xr.26   Xr.27   Xr.28
StdDev: 1.57598 1.57598 1.57598 1.57598 1.57598 1.57598 1.57598 1.57598
   Formula: ~Xr.3 - 1 | g.3 %in% g.2 %in% g.1
 Structure: pdIdnot
           Xr.31    Xr.32    Xr.33    Xr.34    Xr.35    Xr.36    Xr.37    Xr.38
StdDev: 20.06377 20.06377 20.06377 20.06377 20.06377 20.06377 20.06377 20.06377
   Formula: ~Xr.4 - 1 | g.4 %in% g.3 %in% g.2 %in% g.1
 Structure: pdIdnot
               Xr.41        Xr.42        Xr.43        Xr.44        Xr.45
StdDev: 0.0001063304 0.0001063304 0.0001063304 0.0001063304 0.0001063304
               Xr.46        Xr.47        Xr.48
StdDev: 0.0001063304 0.0001063304 0.0001063304
   Formula: ~1 | fac %in% g.4 %in% g.3 %in% g.2 %in% g.1
        (Intercept) Residual
StdDev:   0.6621173 1.007227
  Variance function:
 Structure: fixed weights
 Formula: ~invwt 
Fixed effects: y.0 ~ X - 1 
                  Value Std.Error  DF   t-value p-value
X(Intercept)  2.0870364 0.3337787 392  6.252755  0.0000
Xs(x0)Fx1    -0.0000325 0.1028794 392 -0.000316  0.9997
Xs(x1)Fx1     0.3831694 0.0957323 392  4.002509  0.0001
Xs(x2)Fx1     1.4584330 0.3909237 392  3.730736  0.0002
Xs(x3)Fx1    -0.0123951 0.0143162 392 -0.865809  0.3871
 Correlation: 

   
   
   
   
   
   
   
   
   

 		
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