[R] "nlmnib" Package + Hessian Output

Ben Bolker bbolker at gmail.com
Thu Oct 11 04:06:15 CEST 2012

nserdar <snes1982 <at> hotmail.com> writes:

> I need a "Hessian" matrix in "nlmnib" package to discuss whether parameters
> are significant or not. 
> Please let me know how to obtain hessian matrix and how to evaluate the
> significancy of parameters.

  You can get a finite-difference approximation to the hessian
by using the hessian() function (surprisingly enough) in the
numDeriv package.

  You haven't given enough detail about your problem, but you may
want to consider using the mle2() function in the bbmle package, which
will allow you to use nlminb as your optimizer but provides a wrapper
that computes significance tests (against the null hypothesis that 
individual parameters are zero).

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