[R-sig-ME] Science Fair data

[Douglas Bates]

I'm writing a book about lme4 and lmer.  When it gets to the point
where others can read it without too much frowning and scratching of
heads, I will make chapter drafts available.

For the time being you may find the slides from a short course given
last summer informative.  They are at
http://lme4.R-forge.R-project.org/slides/2009-07-21-Seewiesen/

On Wed, Jan 27, 2010 at 2:53 PM, Doug Adams <fog0 at gmx.com> wrote:
> Hi, and thanks again.  That makes sense with the 3 levels of division:
>
> (Intercept) divisionJunior divisionSenior
>     80.306526      -3.252372      -2.694055
>
> ...so that the Junior and Senior levels are both slightly lower than
> the Elementary level.
>
> I'd love to really understand the summary of lmer and what ranef,
> fixef, coef and fitted are extracting - so that probably means I don't
> understand the basics and nomenclature of HLMing as I thought I might
> have.  I took a 1-week class on HLM, and I have the book you (Douglas
> Bates) wrote...  Maybe I just need to study up on things a little
> better!
>
> Anyway, I appreciate your help very much   : )
>
> Doug
>
>
>
> On Wed, Jan 27, 2010 at 8:07 AM, Douglas Bates <bates at stat.wisc.edu> wrote:
>> On Tue, Jan 26, 2010 at 10:10 PM, Doug Adams <fog0 at gmx.com> wrote:
>>> I appreciate that, both of you (& that's ok for the mistake Christopher)   :)
>>
>>> So fixed factors as simply listed by themselves (no 1| notation) and
>>> random effects are listed with appropriate nesting...  I do want to
>>> consider schools as random effects; that will give me the information
>>> I'd like to have about the variability (and reliability too?) of the
>>> schools as they fit into the big picture.
>>
>>> When I use fixef & ranef to extract estimates for division and schools
>>> (& maybe districts eventually too now), am I right in thinking that
>>> the 3 numbers given for each level of division (fixef) are the
>>> intercepts for each level -- as if there were individual OLS
>>> regressions performed for each?
>>
>> Not quite.  They should be labeled "(Intercept)" and something like
>> division2 and division 3.  (By the way, it helps if you quote the
>> output when you want to discussion what particular values mean.)  The
>> (Intercept) coefficient represents the prediction at the first level
>> of the division factor.  The next two coefficients are the change from
>> the first to the second level and from the first to the third level.
>>
>>> And are the random effects for the
>>> schools (ranef) are the slopes associated with those regression lines?
>
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