[R] lmm WITHOUT random factor (lme4)

[Mark Difford]

On Mar 18, 2011; 10:55am Thierry Onkelinx wrote:

>> Furthermore, I get an error when doing an anova between a lm() and a
>> lme() model.

Hi Thierry,

You get this error because you have not done the comparison the way I said
you should, by putting the lme$obj model first in the call to anova(). This
ensures that lme's anova method is invoked, rather than lm's anova method.

You really do need to be careful with this...

## From my original posting
>> ## Compare models with and without random effects 
>> fm <- lm(Reaction ~ Days, sleepstudy) 
>> fm1 <- lme(Reaction ~ Days, random= ~1|Subject, sleepstudy) 
>> anova(fm1, fm)                 ## lme-fitted model must come first

Regards, Mark.

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