Nothing
## ---- include = FALSE---------------------------------------------------------
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>"
)
## ----instalation, eval = FALSE------------------------------------------------
# install.packages("devtools")
# devtools::install_github("ddebeer/scDIFtest")
## ----get-data, eval = FALSE---------------------------------------------------
# install.packages("psychotree", quiet = TRUE)
# data("SPISA", package = "psychotree")
## ----get-data_2, eval = TRUE--------------------------------------------------
data("SPISA", package = "psychotree")
## ----get-responses------------------------------------------------------------
resp <- as.data.frame(SPISA$spisa[,37:45])
## ----get-summary--------------------------------------------------------------
summary(SPISA[,2:6])
## ----get-mirt-----------------------------------------------------------------
library(mirt, quietly = TRUE)
## ----fit-models---------------------------------------------------------------
fit_2PL <- mirt(data = resp,
model = 1,
itemtype = "2PL",
verbose = FALSE)
fit_multiGroup <- multipleGroup(
data = resp, model = 1,
group = SPISA$gender,
invariance = c("free_means",
"slopes",
"intercepts",
"free_var"),
verbose = FALSE)
## ----anova--------------------------------------------------------------------
anova(fit_2PL, fit_multiGroup)
## ----dif-gender---------------------------------------------------------------
library(scDIFtest)
DIF_gender <- scDIFtest(fit_multiGroup, DIF_covariate = SPISA$gender)
## ----print-dif-gender---------------------------------------------------------
DIF_gender
## ----print-dif-gender-selection-----------------------------------------------
print(DIF_gender, item_selection = c("V4", "V7"))
## ----dif-age------------------------------------------------------------------
DIF_age <- scDIFtest(fit_multiGroup, DIF_covariate = SPISA$age)
summary_age <- summary(DIF_age)
summary_age
## ----dif-spon-----------------------------------------------------------------
DIF_spon <- scDIFtest(fit_multiGroup, DIF_covariate = SPISA$spon)
DIF_spon
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