Development of a general nutrition knowledge questionnaire for adults

Objective: This paper describes the development of a reliable and valid questionnaire to provide a comprehensive measure of the nutritional knowledge of UK adults. The instrument will help to identify areas of weakness in people's understanding of healthy eating and will also provide useful data for examining the relationship between nutrition knowledge and dietary behaviour which, up until now, has been far from clear. Design: Items were generated paying particular attention to content validity. The initial version of the questionnaire was piloted and assessed on psychometric criteria, items which did not reach acceptable validity were excluded, and the final 50 item version was administered to two groups differing in nutritional expertise on two occasions to assess the construct validity and test-retest reliability. Setting: The questionnaire was developed in 1994 in the UK. Subjects: Three hundred and ninety-one members of the general public, recruited via their places of work, completed the questionnaire at the piloting stage. The final version was administered to 168 dietetics and computer science students following a university lecture. Results: The internal consistency of each section was high (Cronbach's alpha = 0.70 - 0.97) and the test-retest reliability was also well above the minimum requirement of 0.7. Nutrition experts scored significantly better than computer experts [F(1167)= 200.5, P < 0.001], suggesting good construct validity. Conclusions: The findings demonstrate that the instrument meets psychometric criteria for reliability and construct validity. It should provide a useful scale with which to reassess the relationship between knowledge and dietary behaviour.