Dear guRus:

I am using lmer for a mixed model that includes a random intercept for a 
set of effects that have the same distribution, Normal(0, sig2b).  This set 
of effects is of variable size, so I am using an as.formula statement to 
create the formula for lmer.  For example, if the set of random effects has 
dimension 8, then the lmer call is:

Zs<- paste("Z",1:mb,sep="")
Trendformula <-as.formula(paste("LogY ~ WYear + (1+WYear|Site) +  (1|", 
paste(paste(Zs,collapse="+"), ")")))
fit2.4a<-lmer(Trendformula, data = testsamp)

which, for mb=8, expands to:

fit1<-lmer(LogY ~ WYear + (1 | Site) + (1 | Year) + (1 | Z1+ Z2 + Z3 + Z4 + 
Z5 + Z6 + Z7 + Z8), data = testsamp)


I have no problems with this.  However, if the set of random effects has a 
dimension of 30, then the lmer call is:

fit2<-lmer(LogY ~ WYear + (1 | Site) + (1 | Year) + (1 | Z1+Z2 + Z3 + Z4 + 
Z5 + Z6 + Z7 + Z8 + Z9 + Z10 + Z11 + Z12 + Z13 + Z14 + Z15 +  Z16 + Z17 + 
Z18 + Z19 + Z20 + Z21 + Z22 + Z23 + Z24 + Z25 + Z26 + Z27 + Z28 + Z29+ 
Z30), data = testsamp)

In this case, I get an error because the name "Z1+Z2 + Z3 + Z4 + Z5 + Z6 + 
Z7 + Z8 + Z9 + Z10 + Z11 + Z12 + Z13 + Z14 + Z15 +  Z16 + Z17 + Z18 + Z19 + 
Z20 + Z21 + Z22 + Z23 + Z24 + Z25 + Z26 + Z27 + Z28 + Z29+ Z30" is too long 
to print in the output.   Is there any way to name the random effect in 
lmer so that the shorter (and more descriptive) name may be used and the 
error avoided?   Or is there a way to combine these into a single variable 
prior to the lmer function call?  In SAS, I am able to parameterize these 
as a Toeplitz structure with bandwidth 1.

Thanks for any help.

Leigh Ann Starcevich
Doctoral student
Oregon State University
Corvallis, Oregon
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