genMantelHaenszel {difR} | R Documentation |
Calculates the generalized Mantel-Haenszel statistics for DIF detection among multiple groups.
genMantelHaenszel(data, member, anchor=1:ncol(data))
data |
numeric: the data matrix (one row per subject, one column per item). |
member |
numeric: the vector of group membership with zero and positive integer entries only. See Details. |
anchor |
a vector of integer values specifying which items (all by default) are currently considered as anchor (DIF free) items. See Details. |
This command computes the generalized Mantel-Haenszel statistic (Somes, 1986) in the specific framework of differential item functioning. It forms the basic command
of difGMH
and is specifically designed for this call.
The data are passed through the data
argument, with one row per subject and one column per item. Missing values are not allowed.
The vector of group membership, specified with member
argument, must hold only zeros and positive integers. The value zero corresponds to the reference group,
and each positive integer value corresponds to one focal group. At least two different positive integers must be supplied.
Option anchor
sets the items which are considered as anchor items for computing generalized Mantel-Haenszel statistics. Items other than the anchor items and
the tested item are discarded. anchor
must hold integer values specifying the column numbers of the corresponding anchor items. It is primarily designed to perform
item purification.
A vector with the values of the generalized Mantel-Haenszel DIF statistics.
Sebastien Beland
Centre sur les Applications des Modeles de Reponses aux Items (CAMRI)
Universite du Quebec a Montreal
sebastien.beland.1@hotmail.com
David Magis
Research Group of Quantitative Psychology and Individual Differences
Katholieke Universiteit Leuven
David.Magis@psy.kuleuven.be, http://ppw.kuleuven.be/okp/home/
Gilles Raiche
Centre sur les Applications des Modeles de Reponses aux Items (CAMRI)
Universite du Quebec a Montreal
raiche.gilles@uqam.ca, http://www.er.uqam.ca/nobel/r17165/
Penfield, R. D. (2001). Assessing differential item functioning among multiple groups: a comparison of three Mantel-Haenszel procedures. Applied Measurement in Education, 14, 235-259.
Somes, G. W. (1986). The generalized Mantel-Haenszel statistic. The American Statistician, 40, 106-108.
# Loading of the verbal data data(verbal) attach(verbal) # Creating four groups according to gender (0 or 1) and trait anger score # ("Low" or "High") # Reference group: women with low trait anger score (<=20) group<-rep(0,nrow(verbal)) group[Anger>20 & Gender==0]<-1 group[Anger<=20 & Gender==1]<-2 group[Anger>20 & Gender==1]<-3 # Without continuity correction genMantelHaenszel(verbal[,1:24], group) # Removing item 6 from the set of anchor items genMantelHaenszel(verbal[,1:24], group, anchor=c(1:5,7:24))