Looking for MIRT example of analysis of Mixed-Format tests

[Jim Chen]

I am new to MIRT. I went through few documents and help files and could not find an example of analysis of mixed-format tests using MIRT. Can someone help or shed lights on this? I am familiar with logistic regression and is tempted to using logistic regression for mixed-format test. Anyone has example or sample code of such approach?

[Jim Chen]

On Thursday, November 12, 2015 at 11:50:19 AM UTC-5, Jim Chen wrote:

I am new to MIRT. I went through few documents and help files and could not find an example of analysis of mixed-format tests using MIRT. Can someone help or shed lights on this? I am familiar with logistic regression and is tempted to using logistic regression for mixed-format test. Anyone has example or sample code of such approach?

 

To fix the idea, I used the following two lines, the data object contains 8 items, the first four items are binary, the last four items are assumed to be partial credit. I don't know if the model fitting syntax is correct assuming uni-dimension.

 

  data <- cbind(key2binary(SAT12[1:4], key = c(1, 4, 5, 2)),SAT12[5:8])
  mod <- mirt(data,model=1,itemtype="gpcm")

 

Thanks

 

[Jim Chen]

On Thursday, November 12, 2015 at 11:50:19 AM UTC-5, Jim Chen wrote:

I am new to MIRT. I went through few documents and help files and could not find an example of analysis of mixed-format tests using MIRT. Can someone help or shed lights on this? I am familiar with logistic regression and is tempted to using logistic regression for mixed-format test. Anyone has example or sample code of such approach?

 

mod <- mirt(data,model=1,itemtype="gpcm")

 

the results of coef(mod) show that MIRT treat grades in column 5 to 8 separately with different estimation of d1, d2, ..., d5. instead of just one parameter d1. I am new to IRT model, here I assume that partial credit, for example 4 out of 5, means the probability of success is 0.8.

 

Anyone can shed some lights on this? Thanks

 

[Phil Chalmers]

Jim, 

You're starting to spam everyone with these repeated/quickly sent emails. Please organize your thoughts and questions a little better next time into a single message, and perhaps provide a reproducible example for other to follow.

This is incorrect thinking indeed, and at that I'm not entirely sure what you are asking. I'd recommend looking over the lecture notes on the wiki and perhaps reading over a book/article about IRT before going any further. 

"[P]ractice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may be cast." -- da Vinci

Cheers.

Phil

 

 

Anyone can shed some lights on this? Thanks

 

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