Mixed Effects Model

Hello all:

This is my first foray into mixed effects modelling and I have a couple 
of questions.

I have data that I would like to analyize and I believe that a mixed 
effects model is the proper thing to use:

fixed effects isolate (factor); response plant height

nested factors:
Time Point (TP) nested in Exp
Plant nested in TP

non-nested factor:
Position (leaf position)

I have explicitly nested the TP in Exp by creating an interaction factor 
TP:Exp=EX_TP and explicitly nested TP in PLANT and Exp with the factor 
variable Exp:TP:PLANT=TP_PLANT

I have used the code

lmer(HEIGHT~ISO+(1|EX)+(1|EX_TP)+(1|TP_PLANT)+(1|POSITION), data=z)

to fit this model.  I believe this is the correct specification.  Is 
this correct?

I would also like to be able to fit this in lme (to be used to create a 
decision tree in package REEM tree).  I would like to use the REEM tree 
package to investigate metal concentrations in the data predicting 
isolate incorperating the experimental structure.

Please let me know if any more information is needed to help answer my 
questions.  Thank you in advance for all of the help.
kindest regards,

Stephen Sefick
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Auburn University
Biological Sciences
331 Funchess Hall
Auburn, Alabama
36849
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sas0025 at auburn.edu
http://www.auburn.edu/~sas0025
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