Discrimination parameter

[kerensm]

Hi

In the polytomous model (IRT), I need some guidance on finding the discrimination parameter (slope (a))- which indicates how well items discriminate between different levels of the underlying trait.

I developed a scale and would like to test it.

Thank you very much

Keren

[seol]

Hi kerensm

you can check it by using Distractor analysis within snowIRT module.

Seol

[kerensm]

Would you please explain how to do this and what result displays the parameter?

[kerensm]

I did it. But I do not understand what parameter displays it. The infit for example parameter shows the difficulty.

[seol]

You will find it by using example .omv file in the Data Library.

[kerensm]

Thank you!
what does this error message mean: "data must be data frame or matrix"?

[seol]

Would you send me .omv file that produced error at snow@cau.ac.kr?

[kerensm]

I appreciate your help. Thank you very much.

I'll send the file soon.