Hi all,

     I'm trying out R's optimization functions (nlm() and optim()) in order
to obtain parameter estimates for a combination of distributions.  I've got
my likelihood function, and optim() is happy to provide estimates (nlm()
less so), but I'm concerned that uneven parameter scaling may be influencing
the solutions.  Does anyone know of any good references for application of
nonlinear optimization that address this issue?  Google returns vast
quantities of information on NLM techniques, but I haven't found much on
this topic.  Thanks in advance,

Dave

-- 
Post-doctoral Fellow
Neurology Department
University of Iowa Hospitals and Clinics
davideugenewarren@gmail.com

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