There is no function in R AFAIK, where an IRT model is estimated using the NPMML method (non-parametric marginal maximum likelihood). All MML methods in R assume the population distribution is normal.
Now, the jml function in the MiscPsycho package uses joint maximum likelihood for estimating item parameters for the Rasch model. Now, jml makes no particular assumptions about the shape of the proficiency distribution or the shape of the item distribution. However, jml estimates are not consistent, but they tend to the true parameter with less bias as the number of items increases. So, it may be useful for you in some regard. -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Helen Lisman Sent: Wednesday, March 10, 2010 3:03 PM To: r-help@r-project.org Subject: Re: [R] help R non-parametric IRT simulation Hello R, I am looking for non-parametric simulation in IRT. Is there any IRT package that does non-parametric simulation? helen L [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
