[R-sig-ME] Nutrition questionnaire data

Doug Adams fog0 at gmx.com
Sun Jun 13 05:55:53 CEST 2010


Hello,

It's been a while since I've posted, although I've been using R
sig-mixed-models as a reference a lot lately.

I've got some data from a questionnaire that I'd like to analyze, and
I want to make sure my syntax is right.  There were multiple groups of
subjects (residents, medical students...) being surveyed, and the
questions were also grouped into subscales.  So basically, I have the
"response" for each question & for each subject, and questions &
subjects are crossed.  Further, questions are nested within subscales,
while subjects are nested within groups -- and groups & subscales are
crossed.

So here's kind of what it looks like:

                               subscale 1
subscale 2                      subscale 3
                               q1      q2      q3      q4      q5
q6      q7      q8      q9      q10     q11     q12
Attending         s1      #       #       #       #       #       #
   #       #       #       #       #       #
                       s2      #       #       #       #       #
#       #       #       #       #       #       #
                       s3      #       #       #       #       #
#       #       #       #       #       #       #
Student            s4      #       #       #       #       #       #
    #       #       #       #       #       #
                       s5      #       #       #       #       #
#       #       #       #       #       #       #
                       s6      #       #       #       #       #
#       #       #       #       #       #       #
Resident          s7      #       #       #       #       #       #
   #       #       #       #       #       #
                       s8      #       #       #       #       #
#       #       #       #       #       #       #
                       s9      #       #       #       #       #
#       #       #       #       #       #       #


I hope that comes out right ASCII-wise in this post!   : )   Anyway,
there are more subjects and questions and such than in this little
visual of course.  Is this correct?

lmer(response ~ group + (1|subject) + (1|question), data=NL, REML=TRUE)

Thanks so much,
Doug Adams


P.S. - If there's a reference for the modeling syntax used in R -- or
in lme4 specifically if need be -- and how each operator works, please
let me know.  For example, if there were a help document that says
things like " A\B means A is nested within B ," or " the | symbol
denotes the the following factor is at a higher level in the model, "
etc., that would be so helpful.  I've learned a lot from context, from
Pinheiro & Bates (though that's for nlme), and from this forum, but I
haven't been able to find something like a formula syntax reference
like that.




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