[R-sig-ME] equality constraints in lmer/lme4

[Ewart Thomas]

j-p, if the constrained model you want is really 

fm <- lmer ( Outcome ~ Xt  + ( 1 | Subject ), data = mydata),

where Xt = X1 + X2, then why not define Xt as such and take it from there.
ewart

On Oct 20, 2013, at 6:52 PM, Jean-Philippe Laurenceau wrote:

> Dear R-sig-ME list--
> 
> When specifying the following lmer model, I get intercept fixed and random effects, a fixed effect for the X1 predictor, and a fixed effect for the X2 predictor.
> 
> fm <- lmer ( Outcome ~ X1 + X2 + ( 1 | Subject ), data = mydata)
> 
> My question: is there a way to ask lme4 to re-estimate this model but set an equality constraint on the effects of X1 and X2, such that their estimates would be equal to each other?
> 
> Thanks for your time, J-P
> 
> Jean-Philippe Laurenceau, Ph.D.
> Department of Psychology
> University of Delaware
> 
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