One major aim of international large-scale assessments (ILSA) like PISA is to monitor changes in student performance over time. To accomplish this task, a set of common items (i.e., link items) is repeatedly administered in each assessment. Linking methods based on item response theory (IRT) models are used to align the results from the different…

Item nonresponses are prevalent in standardized testing. They happen either when students fail to reach the end of a test due to a time limit or quitting, or when students choose to omit some items strategically. Oftentimes, item nonresponses are nonrandom, and hence, the missing data mechanism needs to be properly modeled. In this paper, we…

Since 2000, the PISA test implemented by OECD has become the prime benchmark for international comparisons in education. The 2015 PISA edition introduced methodological changes that altered the nature of its results. PISA made no longer valid non-reached items of the final part of the test, assuming that those unanswered questions were more a…

In educational assessments two types of missing responses can be discerned: items can be "not reached" or "skipped". Both types of omissions may be related to the test taker's proficiency, resulting in non-ignorable missingness. This paper proposes to model not reached and skipped items as part of the response process, using…

When dealing with missing responses, two types of omissions can be discerned: items can be skipped or not reached by the test taker. When the occurrence of these omissions is related to the proficiency process the missingness is nonignorable. The purpose of this article is to present a tree-based IRT framework for modeling responses and omissions…

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…

We investigate the extent to which language versions (English, French and Arabic) of the same science test are comparable in terms of item difficulty and demands. We argue that language is an inextricable part of the scientific literacy construct, be it intended or not by the examiner. This argument has considerable implications on methodologies…