Re: Question about Package ‘mirt’

[Phil Chalmers]

On Wed, Mar 22, 2017 at 10:12 AM, Chinnakrit Kongyoo <kr...@hotmail.co.nz> wrote:

Dear  Phil Chalmers

Greetings from Thailand. My name is Chinnakrit Kongyoo, an M.Ed. Student in Educational Measurement and Evaluation in Thailand. I am interested in item fit statistics. I have studied the Package ‘mirt’ manual and I have questions as follow:

           

1. Can the Item fit statistics in Package ‘mirt’ use for Polytomous IRT such as Graded Response Model, Generalized Partial Credit Model? If it can use for Polytomous IRT, do you have the example of syntax?

There's a polytomous model example in the help(itemfit) help file. 

 

2. Is the 'G2' (McKinley & Mills,1985) similar method to ‘PARSCALE G2’ (Muraki and Bock, 1997)?

Yes. At least it's the same statistic, there may be slight differences that need to be adjusted (e.g., how the bins are formed). But there are other inputs to modify these as well.

 

3. Referring to Package ‘mirt’ page 47 “'S_X2' : Orlando and Thissen (2000, 2003) and Kang and Chen’s (2007) signed chi-squared test (default)”

            In the Package ‘mirt’, Is the 'S_X2'  (Orlando and Thissen, 2000, 2003) the same as method in 'S_X2'  (Kang and Chen’s, 2007)? or Is the 'S_X2'  (Orlando and Thissen, 2000, 2003) the same as computation or formula in 'S_X2'  (Kang and Chen’s, 2007)?

They are synonymous. The kind of table collapsing Kang and Chen had to do is not applicable to dichotomous items. HTH.

Phil

 

 

Thank you very much for your time and I look forward to hearing from you.

 

Yours sincerely,

Chinnakrit Kongyoo

[kr...@arts.tu.ac.th]

Dear Phil Chalmers

Do you have a plan to develop PARSCALE G2’ (Muraki and Bock, 1997) in mirt  package?

Best regards,

Chinnakrit Kongyoo

[Phil Chalmers]

Check the itemfit() documentation. 

Phil

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[kr...@arts.tu.ac.th]

Dear Phil Chalmers

Thank you so much. I have checked the itemfit() documentation. There is only 'G2' (McKinley & Mills,1985) in package "mirt", and it doesn't have the PARSCALE G2 (Muraki and Bock, 1997) in package "mirt". 

Best regards,

Chinnakrit Kongyoo

Check the itemfit() documentation. 

Phil

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[Phil Chalmers]

Could you describe what the difference is? As far as I know they are based on the same methodology. 

Phil

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[Linda Pannekoek]

Could anyone tell me what values indicate a good fit (fro G2 and X2 in the mirt fit stats output)?

[Phil Chalmers]

Unless your test length is really small, probably none of those measures. You're better off using the M2() function for such tasks, as well as inspecting things like itemfit(). 

Phil