[R-sig-ME] Fixed effects only model with lme4

Douglas Bates bates at stat.wisc.edu
Sat Jun 6 19:49:37 CEST 2009

On Sat, Jun 6, 2009 at 12:03 PM, Jeroen Ooms<jeroenooms at gmail.com> wrote:
> For my GUI, I would like the user to be able to compare a fixed effects
> model with a random effects model. For example:
> fm0 <- lmer(Reaction ~ Days, sleepstudy);
> fm1 <- lmer(Reaction ~ Days + (1|Subject), sleepstudy);
> anova(fm0,fm1);
> However, this returns the obvious "No random effects terms specified in
> formula" error for the first model. I've also tried fitting the fixed
> effects model with lm:
> fm0 <- lm(Reaction ~ Days, sleepstudy);
> fm1 <- lmer(Reaction ~ Days + (1|Subject), sleepstudy);
> anova(fm0,fm1);

Try listing them the other way around

anova(fm1, fm0)

If the first model in the call to anova is of class "lm" then the
method for that class is the one chosen and that method doesn't know
about models created by lmer.  You must list them so that the lmer
model comes first.

> However, now the anova function starts complaining. Is there a way to
> perform variance analysis on a fixed only model and a random effects model,
> similar to comparing two random effects models?
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