Background: A person's ability to work with and understand numerical information (i.e., numeracy) is increasingly important in everyday health and other decision-making contexts. Several survey measures of numeracy have been developed to address this trend, including the widely used General Numeracy Scale (GNS), which is thematically focused on health decision-making and is assumed to measure a unidimensional construct of numeracy.
Objective: The present research was designed to evaluate this proposed unidimensional structure of general numeracy, for which prior data have given mixed empirical support.
Methods: Three samples completed the GNS, in different forms, and responses were analyzed in terms of underlying factor structure.
Key results: We show that both one-factor and four-factor models of numeracy are plausible based on the GNS (Study 1), and then develop a multiple-choice version of the GNS (i.e., the MC-GNS) that demonstrates some increased clarity in factor structure due to the consistent response format (Study 2). A further study evaluated the convergent and discriminant validity of the MC-GNS (Study 3), finding it to be as good as or better than the prior scale.
Conclusions: Additionally, the MC-GNS is easier for people to take, likely to be less stressful, and easier for practitioners to score. Collectively, this research identifies a problem with the GNS measure, develops improvements to help address this problem, and in the process creates a way to more easily measure numeracy in practical settings. [HLRP: Health Literacy Research and Practice. 2019;3(3):e174-e180.].
Plain language summary: Numeracy is important across health contexts. Prevalent numeracy scales assumedly measure a single construct but empirical support for this is lacking. We find both one- and four-factor models are consistent with one scale and develop a revision that clarifies this structure without sacrificing validity. This revised numeracy scale is easier to administer and score, and therefore preferable in practical settings.