[R-sig-ME] R-sig-mixed-models Digest, Vol 82, Issue 31

[Cole, Tim]

Probably easier, if X1 and X2 are continuous, would be

fm <- lmer ( Outcome ~ I(X1 + X2) + ( 1 | Subject ), data = mydata)

Best wishes,
Tim Cole

On Mon, 21 Oct 2013, David Duffy wrote:

>On Mon, 21 Oct 2013, Jean-Philippe Laurenceau wrote:
>
>>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?
>
>Create the appropriate composite dummy variable (lmer doesn't offer LISREL
>style constraints). For instance, if X1, X2 are categorical then X1=A
>X2=A -> dummy.A=2, dummy.B=0...
>
>Cheers, David Duffy.
-- 

Tim.Cole at ucl.ac.uk <mailto:Tim.Cole at ich.ucl.ac.uk> Phone +44(0)20 7905
2666 Fax +44(0)20 7905 2381
MRC Centre of Epidemiology for Child Health
<http://www.ucl.ac.uk/ich/research-ich/mrc-cech>
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