Re: [R] maximum-likelihood-estimation with mle()

2015-09-12 Thread Ben Bolker
peter dalgaard gmail.com> writes: > > You are being over-optimistic with your starting values, and/or > with constrains on the parameter space. > Your fit is diverging in sigma for some reason known > only to nonlinear-optimizer gurus... > > For me, it works either to put in an explicit > c

Re: [R] maximum-likelihood-estimation with mle()

2015-09-11 Thread peter dalgaard
You are being over-optimistic with your starting values, and/or with constrains on the parameter space. Your fit is diverging in sigma for some reason known only to nonlinear-optimizer gurus... For me, it works either to put in an explicit constraint or to reparametrize with log(sigma). E.g.

[R] maximum-likelihood-estimation with mle()

2015-09-11 Thread Ronald Kölpin
Hi everyone, I have a problem with maximum-likelihood-estimation in the following situation: Assume a functional relation y = f(x) (the specific form of f should be irrelevant). For my observations I assume (for simplicity) white noise, such that hat(y_i) = f(x_i) + epsilon_i, with the epsilon_i