inst/ShinyItemAnalysis/sc/dif/cum.R

In patriciamar/ShinyItemAnalysis: Test and Item Analysis via Shiny

library(difNLR)

# loading data
data(dataMedicalgraded, package = "ShinyItemAnalysis")
data <- dataMedicalgraded[, 1:100]
group <- dataMedicalgraded[, 101]

# DIF with cumulative logit regression model
(fit <- difORD(
  Data = data, group = group, focal.name = 1, model = "cumulative",
  type = "both", match = "zscore", p.adjust.method = "none", purify = FALSE
))

# estimated parameters in IRT parametrization
coef(fit, SE = TRUE, simplify = TRUE, IRTpars = TRUE, CI = 0)
# estimated parameters in intercept/slope parametrization
coef(fit, SE = TRUE, simplify = TRUE, IRTpars = FALSE, CI = 0)