LassoData: Rearrange the data matrix for the Detection of DIF using the...

In difR: Collection of Methods to Detect Dichotomous and Polytomous Differential Item Functioning (DIF)

Rearrange the data matrix for the Detection of DIF using the Lasso Approach (Magis et al. (2015)

Description

A Function that rearrange the matrix to use the lasso DIF detection for dichotomous items.

Usage

LassoData(Data, group)

Arguments

Data	numeric: either the data matrix only, or the data matrix plus the vector of group membership.
group	numeric or character: either the vector of group membership or the column indicator (within Data) of group membership.

Details

This function rearranges the data matrix for use in lasso-based DIF detection with dichotomous items. It requires a matrix of dichotomous item responses and a vector indicating group membership.

Value

A matrix of five columns where, respectively,:

SCORE	is the total score.
GROUP	is the group membership.
PERS	is the number of the respondent.
Y	is the dichotomous answer to the item. Only "0" and "1" are allowed.
ITEM	is the item name (must be a character).

Author(s)

Sebastien Beland
Faculte des sciences de l'education
Universite de Montreal (Canada)
[e-mail]
Carl F. Falk
Department of Psychology
McGill University (Canada)
[e-mail], https://www.mcgill.ca/psychology/carl-f-falk

References

Magis, D., Tuerlinckx, F., & De Boeck, P. (2015). Detection of Differential Item Functioning Using the Lasso Approach. Journal of Educational and Behavioral Statistics, 40(2), 111–135. https://doi.org/10.3102/1076998614559747

Examples

## Not run: 

# Example with the verbal data

data(verbal)

LassoData(Data=verbal[,1:24], group=verbal[,26])

# Example with SimDichoDif to generate uniform DIF

It   <- 15 # number of items
ItDIFa <- NULL
ItDIFb <- c(1,3)
NR   <- 100 # number of responses for group 1 (reference)
NF   <- 100 # number of responses for group 2 (focal)
a    <- rep(1,It)          
b    <- rnorm(It,1,.5)  
Gb   <- rep(2,2)           # Group value for U-DIF
Ga   <- 0                  # Group value for NU-DIF: need to be fix to 0 for U-DIF
Out1 <- SimDichoDif(It,ItDIFa,ItDIFb,NR,NF,a,b,Ga,Gb)
Data<-Out1$data[,1:15]
Member<-Out1$data[,16]

LassoData(Data=Data, group=Member)

 
## End(Not run)
 

difR documentation built on June 8, 2025, 1:03 p.m.