Measuring the mathematics abilities of students with special education needs through a computer-based multilevel adaptive test

In this paper we present results on the estimation of mathematics skills of Italian grade 10 students with special educational needs. The estimation was carried out by means of a com-puter based multilevel adaptive test 1 - 3 - 3 (MST) constructed within the framework of a doctoral research in Social, Developmental and Educational Research Psychology. An item bank was used to construct the MST test. Verification of the unidimensionality of the bank was done through exploratory factor analyses (EFA) and analysis of model fit indices with Rasch's model (Rasch, 1960) being calibrated. Verification of the best measurement properties of the test compared to a linear test was performed by comparing information functions. It is shown that this type of test is able to provide estimates of the ability of students with a con-siderable level of accuracy, even at the extremes of the range of abilities and not only in a neighborhood of the mean value. In particular it was observed that the test is also suitable for students with special educational needs. Such students are distributed across all ability levels, although the majority of them are in the low ability range.