MLoef {eRm}  R Documentation 
This LikelihoodRatioTest is based on item subgroup splitting.
MLoef(robj, splitcr = "median")
robj 
An object of class 
splitcr 
Split criterion to define the item groups.

This function implements a generalization of the MartinLöf test for polytomous items as proposed by Christensen, Bjørner, Kreiner & Petersen (2002), but does currently not allow for missing values.
If the split criterion is "median"
or "mean"
and one or more items' raw scores are equal the median resp. mean, MLoef
will assign those items to the lower raw score group.
summary.MLoef
gives detailed information about the allocation of all items.
summary
and print
methods are available for objects of class 'MLoef'
.
An ‘exact’ version of the MartinLöf test for binary items is implemented in the NPtest
function.
MLoef
returns an object of class MLoef
containing:
LR 
LRvalue 
df 
degrees of freedom 
p.value 
pvalue of the test 
fullModel 
the overall Rasch model 
subModels 
a list containing the submodels 
Lf 
loglikelihood of the full model 
Ls 
list of the sub models' loglikelihoods 
i.groups 
a list of the item groups 
splitcr 
submitted split criterion 
split.vector 
binary allocation of items to groups 
warning 
items equalling median or mean for the respective split criteria 
call 
the matched call 
Marco J. Maier, Reinhold Hatzinger
Christensen, K. B., Bjørner, J. B., Kreiner S. & Petersen J. H. (2002). Testing unidimensionality in polytomous Rasch models. Psychometrika, (67)4, 563–574.
Fischer, G. H., and Molenaar, I. (1995). Rasch Models – Foundations, Recent Developements, and Applications. Springer.
Rost, J. (2004). Lehrbuch Testtheorie – Testkonstruktion. Bern: Huber.
# MartinLöftest on dichotomous Rasch model using "median" and a userdefined
# split vector. Note that group indicators can be of character and/or numeric.
splitvec < c(1, 1, 1, "x", "x", "x", 0, 0, 1, 0)
res < RM(raschdat1[,1:10])
MLoef.1 < MLoef(res, splitcr = "median")
MLoef.2 < MLoef(res, splitcr = splitvec)
MLoef.1
summary(MLoef.2)