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.