Abstract:  Item position effect (IPE) refers to the item parameter non-invariance when the same item is placed at different positions of the tests, after controlling for the influence of random errors. The presence of IPE causes the violation of the critical parameter invariance assumption made in item response theory, making the applications such as test equating and computerized adaptive testing at risk. At present, the existing researches in this field mainly focus on the detection and modeling of IPE. However, more research efforts are needed to further explain the consequences of the detected IPE and to provide an in-depth discussion of IPE under different scenarios, which is of great importance to both basic research and practical applications.

Key words:  item position effect, parameter invariance, test fairness, explanatory item response theory, multilevel item response models