Psychometric properties of the short-form CART: Investigating its dimensionality through a Mokken Scale analysis

Abstract

Rationality is considered an important trait for functioning in modern society, as it is thought to be necessary for making judgments and decisions. Rationality aligns well with ambitions in higher education for teaching students to be critical thinkers and decision makers. The short-form Comprehensive Assessment of Rational Thinking (CART) might therefore be suitable for measuring this ability in higher education. Subtest total scores are used and interpreted as distinguishable units of measurement, representing single subconstructs within the concept of rationality. In this study, we explored whether the subtests can indeed be interpreted as unidimensional scales. We assessed the subtests’ dimensionality by performing a Mokken scale analysis using the performance data of 185 students of higher education on a Dutch translation of the short-form CART. For two subtests, all items formed a single ordinal scale. For three subtests, a subset of items formed a scale. For seven subtests, no items, nor any subset of items, formed a unidimensional scale. In its current form, then, not all short-form CART subtest scores could be meaningfully interpreted as measures of constituent parts of rationality, limiting its use for assessment in higher education.