[R] imposing constraints on the covariance matrix of random effects in lme4?

[JVVerkuilen]

Hello all,

I am using lme4 to fit some mixed logistic regressions. I need to
impose an identification constraint of the following form:

(1        sig12)
(sig12  sig22)

and have not figured out how to do it, i.e., sig11 = 1 but the rest of
the parameters are free to vary. Is this possible and, if so, how?

I've been looking through the archive and help to no avail, but
perhaps I'm just missing something.

Thanks for any help,

Jay
-- 
JVVerkuilen. PhD
jvverkuilen at gmail.com

"If you've been playing poker for half an hour and you still don't
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