| data_sim_Rasch {DIFtree} | R Documentation |
Simulated Data Set with Dichotomous Items
Description
The data set is simulated from a Rasch model where some items exhibit differential item functioning. Existing differences in item difficulties are simulated by step-functions. The true, simulated DIF structure is described in Tutz and Berger (2015), Section 4.2.
Usage
data(data_sim_Rasch)
Format
A data frame containing 500 observations on 5 variables:
Y matrix with binary 0/1 response for 20 items
x1 binary covariate 1
x2 metric covariate 1
x3 binary covariate 2
x4 metric covariate 2
References
Berger, Moritz and Tutz, Gerhard (2016): Detection of Uniform and Non-Uniform Differential Item Functioning by Item Focussed TreesJournal of Educational and Behavioral Statistics 41(6), 559-592.
Tutz, Gerhard and Berger, Moritz (2016): Item focussed Trees for the Identification of Items in Differential Item Functioning, Psychometrika 81(3), 727-750.
Examples
data(data_sim_Rasch)
Y <- data_sim_Rasch[,1]
X <- data_sim_Rasch[,-1]
hist(rowSums(Y), breaks = 0:19 + 0.5)
summary(X)