Difficulty of healthy eating: a Rasch model approach.

This study aims to measure the difficulty of healthy eating as a single latent construct and, within that, assess which dietary guidelines consumers find more or less difficult to comply with using the Rasch model approach. Participants self-reported their compliance with 12 health-promoting dietary recommendations related to cooking methods and consumption of specific food items. Data were drawn from a survey elicited using a longitudinal consumer panel established in the City of Guelph, Ontario, Canada in 2008. The panel consists of 1962 randomly-selected residents of Guelph between the age of 20 and 69 years. The response rate was equal to 68 percent. The main assumptions of the Rasch model were satisfied. However, subsequent differential item functioning analysis revealed significant scale variations by gender, education, age and household income, which reduced the validity of the Rasch scale. Conversely, these scale variations highlight the importance of socio-economic and demographic factors on the difficulty of healthy eating.