item.DIF: Detect Differential Item Functioning

In jeppebundsgaard/RDigram: Analysis of Items from Tests and Surveys

Detect Differential Item Functioning

Description

Detect Differential Item Functioning (DIF)

Usage

item.DIF(do=NULL,resp=NULL,items=1:do$recursive.structure[1],exo=(do$recursive.structure[1]+1):do$recursive.structure[2],verbose=T)

Arguments

do	an object of class digram.object
resp	A data.frame or matrix of recoded data (only used if do is NULL)
items	A vector of columns from the recoded data to include as items in the analysis or a character vector of variable labels
exo	A vector of columns from the recoded data to include as exogenous variables in the analysis or a character vector of variable labels
p.adj	the kind of multiple p-value testing adjustment to be used (one of "BH","holm", "hochberg", "hommel", "bonferroni", "BY", "none").
max.name.length	Maximum length of item names (to be printed in tables)
digits	Number of digits in table
only.significant	Only list fit values significantly different from 1
verbose	Print results
extra.verbose	Print warnings in PDF and HTML-output
saved.result	To avoid repeated calculation, you can provide a saved version of the analysis (returned from item.DIF())
caption	Caption for the DIF table (in Rmarkdown)

Details

Second step in item screening: Analysis of DIF and local dependency

C2

Y_i \perp X_j \mid S for all i = 1 \ldots k and j = 1 \ldots m

C4

Y_a \perp Y_b \mid R_a and Y_a \perp Y_b \mid R_b

Conditional independence of A and B given C is denoted as A \perp B \mid C. Use local.independence() to detect local dependency

If you want to use this function in R Markdown or Bookdown, you need to use xelatex as latex engine, and you need to force dev to use cairo_pdf or png. Add this in you yaml header:

output:
pdf_document:
latex_engine: xelatex

Add this in your setup chunk:

knitr::opts_chunk$set(echo = TRUE, dev = "cairo_pdf", dpi = 300)

Value

Returns a list of DIF-information

Author(s)

Jeppe Bundsgaard [e-mail]

References

Kreiner, S. & Christensen, K.B. (2011). Item Screening in Graphical Loglinear Rasch Models. Psychometrika, vol. 76, no. 2, pp. 228-256. DOI: 10.1007/s11336-9203-Y

See Also

partgam_LD(), local.independence()

Examples

item.DIF(DHP)

jeppebundsgaard/RDigram documentation built on Oct. 29, 2023, 7:15 p.m.