R/itemFitTestGardener.R

In joakimwallmark/PolyOptimalIRT:

# Implements S-X^2
# Each item in U starts with 0
# mincell is minimum allowed cell value before collapse
itemFitTestGardener <- function(model, data, items = 1:ncol(data), mincell = 1, kernelDensity = F) {
    # get wdfList for last cycle
    parList <- model$parList[[length(model$parList)]]
    # create list of model probabilities for each item
    probMatList <- list()
    itemDFs <- vector("numeric", length = ncol(data))
    for (item in items) {
        probMatList[[item]] <- t(parList$WfdList[[item]]$Pmatfine)
        # no of basis splines times categories - 1 is DF?
        itemDFs[item] <- parList$WfdList[[item]]$Wfd$basis$nbasis*(nrow(probMatList[[item]])-1)
    }

    density <- if (kernelDensity)
        cbind(0:100, density(parList$theta, from = 0, to = 100, n=101)$y)
    else
        cbind(0:100, parList$densfine)

    return(itemFit(data, probMatList, density, itemDFs))
}