Dear R users,
I have encountered some error in finding factor scores/ person ability in
item response theory.
I tried a few times using ltm and mirt package but it still gave me error.
#TRY #1 - Fit GPCM model using ltm
> irt_model <- gpcm(response_matrix)
> irt_person_abilities <- fscores(irt_model)
*Error in object@Model : *
* no applicable method for `@` applied to an object of class "gpcm"*
#TRY #2 - Fit GPCM model using ltm
> irt_model <- gpcm(data = HT, constraint = "1PL")
> irt_person_abilities <- factor.scores(irt_model)
*Error in factor.scores(irt_model) : *
* argument "f" is missing, with no default*
#TRY #3 - Fit GPCM model using mirt
> irt_model <- mirt(data = HT, model = "gpcm", itemtype = "graded")
*Error in model$x[i, "Type"] : subscript out of bounds*
*In addition: Warning message:*
*In cbind(model$x, OptionalGroups = "") :*
* number of rows of result is not a multiple of vector length (arg 2)*
> irt_person_abilities_dim1 <- fscores(gpcm_model, method = "EAP", dims = 1)
*Error in object@Model : *
* no applicable method for `@` applied to an object of class "gpcm"*
I am not sure which package is suitable with my data (Polytomous - Partial
Credit Model) and why it always turns out to be an error.
Thank you very much for any help given.
Azila.
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