Hi Rachel,

Do you get what you need with

lmer(H.y.~(cond/patient)*stance + (1|subj), data=H)

? That should give you the comparison between patient groups at each level
of Condition (the cond1:patient1, cond2:patient2, and cond2:patient3 that
you were looking for). (And I guess it will also give interactions between
those and Stance; I haven't ever run a model like that myself, though.)

I'm new myself to mixed effects models and so I'm not sure if you need to
do anything different from what I did to deal with the fact that your
"cond" variable is between-subjects (in my data that started this thread,
all the variables were within-subjects). So you may want to check about
that as well.

Best of luck,
Steve



Message: 73
Date: Tue, 11 Sep 2012 00:22:21 -0700 (PDT)
From: semperparatus <robe0899@umn.edu>
To: r-help@r-project.org
Subject: Re: [R] Contrasts for 2x4 interaction in mixed effects model
Message-ID:
        <CAN_X31jAmDXurD2bMoQJQ8W=FEnC8hw8AT+eVJSFabvAHOFmdg@mail.gmail.com>
Content-Type: text/plain

Thanks for your response. First time posting on any R forum, and apparently
I didn't read carefully enough to see the difference in my model. I much
appreciate the quick response.

On Tue, Sep 11, 2012 at 2:16 AM, David Winsemius [via R] <
ml-node+s789695n4642723h15@n4.nabble.com> wrote:

>
> On Sep 10, 2012, at 5:59 PM, semperparatus wrote:
>
> > I want to change it because I don't want to compare in this instance
> between
> > conditions, but I simply want to see the contrast t-statistic between
> > patient and control at every level of condition (1, 2, and 3).
> >
> >> From there I'd like to be able to plot the t-statistic for the contrast
> > between patient and control at level 1 of conditon, level 2 of
> condition,
> > and level 3 of condition, each with error bars.
> >
> > In the post I responded to the output gave fixed effect output for
> > SecA:Fir1, SecB:Fir1, SecC:Fir1, and SecD:Fir1.  I'm hoping to get the
> same
> > sort of output but for mine it would be Cond1:Patient1,  Cond2:Patient1,
> > Cond3:Patient1.
>
> It does not appear that you have the same situation as was being discussed
> earlier:
>
> Yours was:
>
> ' *When I tried using the syntax you used with my model:
> lmer(H.y. ~ patient*stance*cond  +(cond/patient) + (1|subj), data=H), I
> got this
> result, which seems to be using condition 1 as a part of the baseline. Any
> idea how to change that?*'
>
> The other was:
>
> test <- lmer(Latency ~ (Nuisance1*Nuisance2) + (Sec/Fir) + (1|Subject) +
> (1|Item), datatotest)
>
> He had separated his nuisance parameters from the 2 variables (Sec and
> Fir)  for which he was interested in examining contrasts.
>
> PLEASE learn to include context.
>
>
>
> --
> David Winsemius, MD
> Alameda, CA, USA

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