Young adolescents’ engagement in dietary behaviour – the impact of gender, socioeconomic status, self-efficacy and scientific literacy. Methodological aspects of constructing measures in nutrition literacy research using the Rasch model. Abstract Objective: This study validates a revised scale measu

Objective: This study validates a revised scale measuring persons’ level of the ‘engagement in dietary behaviour’ aspect of ‘critical nutrition literacy’ and describes how background factors affect this aspect of Norwegian tenth grade students’ nutrition literacy. Design: Data were gathered electronically during a field trial of a standardised sample test in science. Test items and questionnaire constructs were distributed evenly across four electronic field test booklets. Data management and analysis were performed using RUMM2030 and SPSS20. Setting: Students responded on computers at school. Subjects: Seven hundred and forty tenth grade students at twenty-seven randomly sampled public schools were enrolled in the field test study. The engagement in dietary behaviour scale and the self-efficacy in science scale were distributed to one hundred and seventy-eight of these students. Results: The dietary behaviour scale and the self-efficacy in science scale came out as valid, reliable and well-targeted instruments usable for the construction of measurements. Conclusions: Girls and students with high self-efficacy reported higher engagement in dietary behaviour than other students. Socioeconomic status and scientific literacy – measured as ability in science by applying an achievement test – did not correlate significantly different from zero with students’ engagement in dietary behaviour. Introduction Aims The ultimate goals of public health nutrition research are to describe nutrition-related public health issues by applying valid and reliable instruments and enabling citizens and policy makers to take advantage of the findings. This Norwegian study is a quantitative study aimed at describing and understanding, using reliable and valid measures, tenth grade students’ attitudes toward nutrition-related public health issues. The first objective is to validate a revised scale assessing individuals’ engagement in dietary behaviour at the personal, social and global level (1). The second objective is to describe how different factors affect responses to the engagement in the dietary behaviour scale. 2 Domains of nutrition literacy and engagement in the dietary behaviour (EDB) scale Health literacy is ‘the degree to which individuals have the capacity to obtain, process, and understand basic health information and services needed to make appropriate health decisions’ (2). Health literacy is claimed to be a stronger predictor of health than age, income, employment, education, and cultural background (3). Nutrition literacy, being an important dimension of people’s health literacy, has been defined as ‘the ability to find and elaborate on nutrition information and make conclusions regarding health issues’ (4, 5). There are three major domains of nutrition literacy, which are referred to as functional nutrition literacy (FNL), interactive nutrition literacy (INL) and critical nutrition literacy (CNL) (5). FNL refers to proficiency in applying basic literacy skills while INL comprises the cognitive and interpersonal communication skills needed to seek nutrition information and interact appropriately with nutrition counsellors. The CNL domain covers the broad topics ‘critically evaluating nutrition information and advice’ and ‘engagement in dietary behaviour’. The first of these topics comprises the skills to ‘justify premises for and evaluate the sender of nutrition claims’ and ‘identify scientific nutrition claims’. Being critical nutrition literate therefore means being proficient in evaluating scientific enquiry and interpreting data and evidence scientifically, which actually means being scientifically literate as described by PISA (7). The second topic covered by the domain CNL includes the capability to ‘be concerned about dietary behaviours’ and ‘engage in processes to improve dietary behaviours’ (4, 6). The engagement in dietary behaviour (EDB) scale was developed to assess the EDB part of individuals’ CNL. By hypothesising individuals’ scientific literacy as a predictor that facilitates the forming of persons’ CNL (8), and viewing scientific literacy as a mediator that helps implement the ideas on what scientific knowledge ‘is’ and how scientific knowledge forms and develops, we conducted analyses of an achievement test assessing ability in science and a scale measuring SE in science. Self-efficacy (SE) in science, scientific literacy and socioeconomic status (SES) Self-efficacy (SE), being part of individuals’ self-regulation (9), represents the personal perception of external social factors (10, 11). In social-cognitive models of health behaviour