Mathematics proficiency involves several content domains and processes at different levels. This essentially means that mathematics ability is a complex latent variable. In standardised testing, the complex, and unobserved, latent constructs underlying a test are traditionally appraised by expert panels through subjective measures. In the present research, we deal with the issue of dimensionality of the latent structure behind a test measuring the mathematics ability of Italian students from a statistical and objective point of view, within an IRT framework. The data refer to a national standardised test developed and collected by the Italian National Institute for the Evaluation of the Education System (INVALSI), and administered to lower secondary school students (grade 8). The model we apply is based on a class of multi- dimensional latent class IRT models, which allows us to ascertain the test dimensionality based on an explorative approach, and by concurrently accounting for non-constant item discrimination and a discrete latent variable formulation. Our results show that the latent abilities underlying the INVALSI test mirror the assessment objectives defined at the national level for the mathematics curriculum. We recommend the use of the proposed extended IRT models in the practice of test construction, primarily—but not exclusively—in the educational field, to support the meaningfulness of the inferences made from test scores about students’ abilities.
A multidimensional IRT approach for dimensionality assessment of standardised students’ tests in mathematics
GNALDI, MICHELA
2017
Abstract
Mathematics proficiency involves several content domains and processes at different levels. This essentially means that mathematics ability is a complex latent variable. In standardised testing, the complex, and unobserved, latent constructs underlying a test are traditionally appraised by expert panels through subjective measures. In the present research, we deal with the issue of dimensionality of the latent structure behind a test measuring the mathematics ability of Italian students from a statistical and objective point of view, within an IRT framework. The data refer to a national standardised test developed and collected by the Italian National Institute for the Evaluation of the Education System (INVALSI), and administered to lower secondary school students (grade 8). The model we apply is based on a class of multi- dimensional latent class IRT models, which allows us to ascertain the test dimensionality based on an explorative approach, and by concurrently accounting for non-constant item discrimination and a discrete latent variable formulation. Our results show that the latent abilities underlying the INVALSI test mirror the assessment objectives defined at the national level for the mathematics curriculum. We recommend the use of the proposed extended IRT models in the practice of test construction, primarily—but not exclusively—in the educational field, to support the meaningfulness of the inferences made from test scores about students’ abilities.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
