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The Influence Of Equating Methodology On Reported Trends In Pisa, Eveline Gebhardt, Ray Adams

Prof Ray Adams

In 2005 PISA published trend indicators that compared the results of PISA 2000 and PISA 2003. This paper explores the extent to which the outcomes of these trend analyses are sensitive to the choice of test equating methodologies, the choice of regression models and the choice of linking items. To establish trends, PISA equated its 2000 and 2003 tests using a methodology based on Rasch Modelling that involved estimating linear transformations that mapped 2003 Rasch-scaled scores to the previously established PISA 2000 Rasch-scaled scores. This paper compares the outcomes of this approach with an alternative, which involves the joint Rasch …