[R] help R non-parametric IRT simulation

[Doran, Harold]

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-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Helen Lisman
Sent: Wednesday, March 10, 2010 3:03 PM
To: r-help at 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

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