The purpose of this study was to examine the use of a misspecified calibration model and its impact on proficiency classification. Monte Carlo simulation methods were employed to compare competing models when the true structure of the data is known (i.e., testlet conditions). The conditions used in the design (e.g., number of items, testlet to…

Standard errors computed according to the operational practices of international large-scale assessment studies such as the Programme for International Student Assessment's (PISA) or the Trends in International Mathematics and Science Study (TIMSS) may be biased when cross-national differential item functioning (DIF) and item parameter drift are…

One major issue with large-scale assessments is that the respondents might give no responses to many items, resulting in less accurate estimations of both assessed abilities and item parameters. This report studies how the types of items affect the item-level nonresponse rates and how different methods of treating item-level nonresponses have an…

Due to the broad acceptance of the Programme for International Student Assessment (PISA) and other comparative studies as instruments of policymaking, its accuracy is essential. This article attempts to demonstrate omissions in the conceptualisation, and consequently in calculation and interpretation, of one of the central points of PISA 2006 and…