[R] Error in analysis of arguments of Rasch

[nor azila]

Dear R users,

I am using ltm and eRm package in analysing my polytomous data for fitting
item response theory and Rasch model, respectively.

I'm having a problem with the error as below;

> library(eRm)
> library(ltm)
> HT <- read.csv("C:/Dropbox/Analysis R_2023/HT.csv")
> response_columns <- HT[, 1:ncol(HT)]
> response_matrix <- as.matrix(response_columns)
> irt_model <- grm(response_matrix)
> rasch_model <- Rasch(response_matrix)
Error in Rasch(response_matrix) : could not find function "Rasch"

Then I changed the arguments of Rasch to RM, but it also turns out an error
as below;

> rasch_model <- RM(response_matrix)
Error in datcheck(X, W, mpoints, groupvec, model) :
  Dichotomous data matrix required!

Is there any problem with the arguments or any other problem with my coding
since errors keep occurring when I want to run Rasch.

Thank you very much for any help given.

Azi.

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