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Effects Of Item Positions On Their Difficulty And Discrimination : A Study In Pisa Science Data Across Test Language And Countries, Luc T. Le

Dr Luc Tu Le

This study was based on a four-cluster rotation design of 13 linked test booklets from PISA 2006 science data. It investigated effects of item positions on their difficulty and discrimination parameter estimates obtained from one and two parameter IRT Partial Credit models. The analyses were done separately for 57 test language groups from 53 countries with a total of about 340,000 students. The results revealed that for all of the test language groups the items tended to become more difficult when they were located later in the test. However, a high linear relationship between the item difficulty estimates by the …