Message-ID: <32ddc391-c0c2-4c8c-6c3b-b086de963d5c@gmail.com>
Date: 2018-08-02T03:57:38Z
From: Ben Bolker
Subject: (no subject)
In-Reply-To: <CAM834XKtXfnLF0NVc98-G8Syu6dUZW20m+-34iqW+E2Dz-xWLQ@mail.gmail.com>
(please keep r-sig-mixed-models in the Cc:)
I'm pretty sure that lmer and lm models are commensurate, in case that
helps. Here's an example rigged to make the random-effects variance
equal to zero, so we can check that the log-likelihoods etc. are identical.
set.seed(101)
dd <- data.frame(y=rnorm(20),x=rnorm(20),f=factor(rep(1:2,10)))
library(lme4)
m1 <- lmer(y~x+(1|f),data=dd,REML=FALSE) ## estimated sigma^2_f=0
m2 <- lm(y~x,data=dd)
all.equal(c(logLik(m1)),c(logLik(m2))) ## TRUE
all.equal(fixef(m1),coef(m2))
anova(m1,m2)
On 2018-08-01 11:41 PM, Peter Paprzycki wrote:
> Thank you. Oh, was just trying to compare my random-effects model to the
> one where my grouping variable (schools) is treated as fixed.
>
> Peter
>
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> On Wed, Aug 1, 2018 at 10:32 PM, Ben Bolker <bbolker at gmail.com
> <mailto:bbolker at gmail.com>> wrote:
>
>
> ? I'm not 100% sure I understand the question, but I think the answer is
> "no": lmer cannot fit a model that doesn't contain any random effects.
> Perhaps you can give more context as to why it won't work for you to
> revert to lm() or plm() in these cases?
>
> On 2018-08-01 11:30 PM, Peter Paprzycki wrote:
> > This is very basic, is there a way to specify in lmer function
> that I would
> > like to run my grouping variable as a fixed factor only, without
> reverting
> > to lm or plm functions. If one does not specify a random variable,
> one gets
> > the error message with lmer function; something that is equivalent
> to the
> > statement, "index = "grouping variable", model = "within"" with
> the plm
> > function.
> >
> >
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> >
> > _______________________________________________
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>
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>
>
> --
>
> Peter Paprzycki, Ph.D.
> Visiting Assistant Professor
> Research Support Center Manager
>
> Educational Research and Administration
> College of Education?and Psychology
> The University of Southern Mississippi
> USM Box 5093; 118 College Drive
> Hattiesburg, Mississippi 39406-0001
> tel. (601)-266-4708
> email: Peter.Paprzycki at usm.edu <mailto:Peter.Paprzycki at usm.edu>
>
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