S3 Method for Extracting Used Item Response Dataset
This S3 method extracts the used dataset with item responses.
IRT.data(object, ...) ## S3 method for class 'din' IRT.data(object, ...) ## S3 method for class 'gdina' IRT.data(object, ...) ## S3 method for class 'gdm' IRT.data(object, ...) ## S3 method for class 'mcdina' IRT.data(object, ...) ## S3 method for class 'reglca' IRT.data(object, ...) ## S3 method for class 'slca' IRT.data(object, ...)
A matrix (or data frame) with item responses and group identifier and weights vector as attributes.
## Not run: ############################################################################# # EXAMPLE 1: Several models for sim.dina data ############################################################################# data(sim.dina, package="CDM") data(sim.qmatrix, package="CDM") dat <- sim.dina q.matrix <- sim.qmatrix #--- Model 1: GDINA model mod1 <- CDM::gdina( data=dat, q.matrix=q.matrix) summary(mod1) dmod1 <- CDM::IRT.data(mod1) str(dmod1) #--- Model 2: DINA model mod2 <- CDM::din( data=dat, q.matrix=q.matrix) summary(mod2) dmod2 <- CDM::IRT.data(mod2) #--- Model 3: Rasch model with gdm function mod3 <- CDM::gdm( data=dat, irtmodel="1PL", theta.k=seq(-4,4,length=11), centered.latent=TRUE ) summary(mod3) dmod3 <- CDM::IRT.data(mod3) #--- Model 4: Latent class model with two classes dat <- sim.dina I <- ncol(dat) # define design matrices TP <- 2 # two classes # The idea is that latent classes refer to two different "dimensions". # Items load on latent class indicators 1 and 2, see below. Xdes <- array(0, dim=c(I,2,2,2*I) ) items <- colnames(dat) dimnames(Xdes)[[4]] <- c(paste0( colnames(dat), "Class", 1), paste0( colnames(dat), "Class", 2) ) # items, categories, classes, parameters # probabilities for correct solution for (ii in 1:I){ Xdes[ ii, 2, 1, ii ] <- 1 # probabilities class 1 Xdes[ ii, 2, 2, ii+I ] <- 1 # probabilities class 2 } # estimate model mod4 <- CDM::slca( dat, Xdes=Xdes) summary(mod4) dmod4 <- CDM::IRT.data(mod4) ## End(Not run)
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