Many educational tests use testlets as a way of
providing context. When testlet effect and item
idiosyncratic features of individual items are both
considered to be the reasons of DIF in many
educational tests using testlets, it is interesting
to investigate the phenomena of DIF amplification
and cancellation resulting from the interactive
effects of these two factors. This research
presented a study based on a multiple-group
testlet item response theory model to examine in
detail different situations of DIF amplification
and cancellation at the item and testlet level using...