The effects of dynamic assessment on Rasch item and person hierarchies in second language testing

Dynamic Assessment (DA) posits that learners’ potential is a reliable measure for predicting learners’ possible improvement in future, i.e., learners’ responsiveness to instruction is seen as a measure of learners’ potential (ZPD). This raises the question whether it is possible to distinguish the quantitative and qualitative effects of DA on the items and persons. To this end two types of Rasch scaling were used to scale sets of wh-type questions and scanning items: (a) students’ answers were treated in a binary correct/incorrect fashion; (b) the change in correctness (if any) was modeled within a Rasch rating scales framework. Using a pre-intervention-post design, Rasch scaling of the data of 42 Iranian university students showed the anticipated quantitative improvement in learners’ performance on the posttest relative to the pretest?for the wh-type questions as well as for scanning items. However, no clear qualitative effects were found as the item and person hierarchies were essentially invariant across the pre- and post-tests. Interestingly, the rating scale formulation showed great promise as measure of ZPD as it proved to be a useful tool to capture the pre- and post-test data simultaneously.