search for: negllh

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2011 Jan 13
1
Weighted Optimization
...uld like to include a weighted likelihood estimation proceedure where the observations have an exponentially decaying weighting rather than the equal weighting implied by a standard MLE approach. The optimization function which leads to my parameter estimates is given by; gh.fit = try(optim(vega, negllh,hessian = se,pdf = gh.pdf, tmp.data = data, transf = transform, const.pars = vars[!opt.pars], silent = silent, par.names = names(vars), ...)) param.est = gh.fit$par In the above, vega are the parameters to estimate and pdf is the GH pdf. This seems to work well for the case wher...
2011 Jan 12
0
Weighted Likelihood Estimation of NIG Dist.
...I've put together some script which gives me the parameters of a modified NIG distribution. Now I'd like to include a weighted vector within the maximization function. The code below gives me parameter estimates which are implicitly equally weighted. nig.par.fit <- try(optim(vega, negllh, hessian = se, pdf = density.nig, tmp.data = data, transf = transform, const.pars = vars[!opt.pars], silent = silent, par.names = names(vars), ...)) vega are the parameters to be fitted. This seems to work reasonably for my equally weighted observatio...