European Journal of Clinical Nutrition (2010) 64, 210–217 & 2010 Macmillan Publishers Limited All rights reserved 0954-3007/10 $32.00 www.nature.com/ejcn ORIGINAL ARTICLE Validity and reliability testing of a short questionnaire developed to assess consumers’ use, understanding and perception of food labels D Mackison1, WL Wrieden2 and AS Anderson1 1Centre for Public Health Nutrition Research, Division of Clinical and Population Sciences and Education (CPSE), University of Dundee, Ninewells Hospital and Medical School, Dundee, UK and 2School of Pharmacy and Life Sciences, The Robert Gordon University, Aberdeen, UK Background: Food labels may have an important function in communicating nutrition information and have considerable potential to influence food choice and dietary behaviour. Objectives: To assess the validity and reliability of a short (self-complete) questionnaire designed to measure consumers’ use and understanding of food labels. Methods: Questionnaire content was determined by gaps highlighted in a literature review of food labelling. Nineteen questions (49 items) assessing frequency of label reading perceived importance of food labels, regularity of dining out, desire to have nutrition information at specific catering outlets and ability to perform nutrition information tasks were formulated and presented on four pages of A4. With the exception of two open-ended questions, all items were presented as closed (field box) structures. Content validity, face validity, item analysis, repeat and internal reliability were assessed. Results: Nutrition experts (26) completed detailed content validity assessment, resulting in high scores for appropriateness, importance and phrasing of questions, although grammar and terminology changes were required. Face validity indicated that the questionnaire was quick to complete (o15 min), easy to follow and comprehensible. Cronbach’s alpha scores (internal reliability) for questions with multiple sections ranged from 0.72 to 0.91, indicating good internal consistency. Repeat reliability testing showed Spearman’s correlation coefficients ranging from 0.51 to 0.97 (all Po0.001) showing high temporal stability. Item Difficulty analysis indicated that questions (Section C only) were at an appropriate level (with P between 20 and 80% for all items). Item discrimination analysis ranged from r ¼ 0.43 to 0.70, highlighting that items were suitable for inclusion. Conclusions: This questionnaire is a suitable tool for assessing consumers’ use, understanding and perception of food labels. European Journal of Clinical Nutrition (2010) 64, 210–217; doi:10.1038/ejcn.2009.126; published online 11 November 2009 Keywords: food labelling; labels; validity; reliability; questionnaire development Introduction Encouragingly, most consumers claim to read food labels often or sometimes (Cowburn and Stockley, 2005; European Food labels are recognized as having a pivotal function in Heart Network, 2003). Available literature, however, suggests communicating nutrition information to consumers and are that while consumers claim to understand the information considered to have the potential to influence food choice they are reading (National Institute of Nutrition, 1999; and dietary behaviour. For the consumer to make healthy Stuart et al., 2004; Food Standards Agency, 2007), their actual food choices, they must be able to locate, read, interpret and understanding is selective (European Heart Network, 2003; understand the information presented on food labels. Cowburn and Stockley, 2005). Consumers display little difficulty judging the nutrient levels of products (Food Correspondence: D Mackison, Division of Clinical and Population Sciences Standards Agency, 2006), yet struggle when asked to perform and Education (CPSE), Centre for Public Health Nutrition Research, University arithmetical calculations and comparisons of different sizes of Dundee, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK. and types of products (Levy and Fein, 1998; Rothman et al., E-mail: [email protected] Received 21 January 2009; revised 16 July 2009; accepted 20 July 2009; 2006). Creating food label information that is easily inter- published online 11 November 2009 preted by consumers requires knowledge of the specific label Short questionnaire assessing food label use and understanding D Mackison et al 211 attributes that consumers read and use. Energy and fat consumers’ desire to have nutrition information available in information are the most commonly read nutrient by the catering establishments. To date, there has been limited consumer (Black and Rayner, 1992; Institute of Grocery research conducted on the British consumers’ views on the Distribution, 1998; Kessler and Wunderlich, 1999; Marietta application of nutrition style information in catering outlets. et al., 1999; Neuhouser et al., 1999; Higginson et al., 2002; The aim of this study was to develop a valid and reliable Krukowski et al., 2006; Mannell et al., 2006); however, we short questionnaire to assess consumers’ use, understanding know little about the consumer’s interpretation of this and perception of food labels in both the retail and catering information and how this influences their food purchase environment. decisions (Grunert and Wills, 2007). In a bid to standardize and ease the delivery of nutri- tion information to the consumer, many countries have Methods adopted mandatory nutrition information on food labels (for example United States, Australia and Canada) (Hawkes, Questionnaire development 2004). If successful, the European Union’s recent proposal for Key areas were identified after a literature review on food a Regulation on the provision of food information to labelling and a draft questionnaire was devised. Five sections consumers (the consolidation and update of the general (A–E) were identified: food-labelling legislation (Council Directive 2000/13/EC of a. Frequency of reading specific attributes on food labels, in the European Parliament and of the Council of 20 March which food labels are read, and importance of food labels 2000, 2000) and the nutrition-labelling legislation (Council b. Frequency of using, views on quantity and perceived Directive 90/496/EEC of 24 September on nutrition labelling importance of nutrition information on food labels for foodstuffs, 1990)) would introduce mandatory nutrition c. Objective assessment of nutrition label tasks labelling on the ‘principal field of vision’ (front of pack) on d. Frequency of using specific catering establishments and all products throughout Member States (EU, 2008). During desire to see nutrition and additional information avail- the consultation and implementation phases of this Regula- able in specific catering establishments tion, increased consumer awareness of nutrition information e. Demographic information on food labels is anticipated as a direct result of media coverage and as labelling changes become prevalent The instrument was intended to be completed indepen- throughout stores. The introduction of a new standardized dently by adults aged 18 years of age and older, and it was nutrition-labelling format provides a valuable opportunity essential that the questionnaire was short in length (four for education interventions focused on food labelling to take sides of A4 paper), quick to complete (o20 min), easy to centre stage. However, before public health practitioners can follow, comprehensible and contained short questions (with tackle educating consumers on the new food-labelling language suitable for the target group). Questionnaire read- formats, it is imperative that we gain a better understanding ability was assessed using the Flesch Reading Ease Score of the consumer’s views on food labels. More information is available on computer software (Microsoft Word 2003) needed on what information consumers actually use, and (Microsoft, 2007). Before validity and reliability testing how consumers use specific information and form food commenced, nutritionists working in the department purchase decisions based on food-labelling information. checked the questionnaire for both content and clarity. Answering these questions will provide useful guidance for Content validity was assessed by experts with a nutrition a tailored food-labelling education campaign that will focus and dietetic background. Both nutrition and dietetic profes- on the key elements pertinent to improving consumers’ label sionals were contacted through an internet listserv group, reading comprehension. the Community Nutrition Group. Using e-mail, a PDF Estimated to be worth d36.6 billion by 2012 (Mintel, version of the draft questionnaire, brief outline of the project 2007), the catering sector has a significant function in and score sheet were distributed to the group. The score everyday life in Britain. Twenty-seven per cent of British sheet listed each question and asked the respondent to score household’s food and drink expenditure is spent on food and the item out of 10 in relation to appropriateness, importance drink (excluding alcohol) outside the home (Defra, 2006). and phrasing. A column was also provided on the score sheet Traditionally, eating out was initiated by a social event or for other/additional comments to be completed as necessary celebratory occasion; however, in today’s fast paced society, by the respondent. Responses were collated and the ques- eating outside the home is often a necessity. As dining out tionnaire was amended as appropriate. increases, it raises the question,