Automation
of the item selection processes for rasch scales by means of exhaustive
search for suitable Rasch models (dichotomous, partial credit,
rating-scale) in a list of item-combinations. The item-combinations to
test can be either all possible combinations or item-combinations can be
defined by several rules (forced inclusion of specific items, exclusion
of combinations, minimum/maximum items of a subset of items). Tests for
model-and item-fit include ordering of the thresholds, itemfit-indices,
likelihood ratio test, Martin Löf test, waldtest, person-item
distribution, person separation index, Rasch PCA, empirical
representation of all raw scores or raschtrees for detecting
differential item functioning. The tests, their ordering and their
parameters can be defined by the user. For parameter estimation and
model tests, functions of the packages eRm, psychotools or pairwise can
be used.