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.
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