Survey completed by adults with low socioeconomic status

Survey completed by adults with middle/high socioeconomic status

The survey is based on the Theory of Planned Behaviour and assesses intention to participate in NutriQuébec as well as attitude, subjective norm, and perceived behavioural control. The salient beliefs underlying the determinants of individual's intention to participate in the NutriQuébec study most frequently cited in the focus groups (from a preliminary elicitation study: 2018-042 A-1/18-05-2018) were used to develop the survey questions. The survey also assesses the preferences regarding the recruitment. Sociodemographic questions are also asked.

Intention will be calculated as the mean of three questions on a five point bipolar Likert scale. The three questions are: 1) I intend to participate in the NutriQuébec study : 1=very unlikely, 2=rather unlikely, 3=neither likely nor unlikely, 4=rather likely, 5=very likely; 2) The chances that I participate in the NutriQuébec study are : 1=very small, 2=rather small, 3=neither high nor small, 4=rather high, 5=very high; 3) I will participate in the NutriQuébec study: 1=very unlikely, 2=rather unlikely, 3=neither likely nor unlikely, 4=rather likely, 5=very likely). Thus, the mean score for intention ranges from 1 to 5, with higher values reflecting a greater likelihood for participation in the NutriQuébec study.

The attitude will be calculated as the mean of three questions on a five point bipolar Likert scale. The three questions are: 1) For me, participating in the NutriQuébec study would be...: 1=very unpleasant, 2=rather unpleasant, 3=neither pleasant nor unpleasant, 4=rather pleasant, 5=very pleasant; 2) For me, participating in the NutriQuébec study would be...: 1=very useless, 2=rather useless, 3=neither useful nor useless, 4=rather useful, 5=very useful; 3) For me, participating in the NutriQuébec study would be…: 1=very unsatisfactory, 2=rather unsatisfactory, 3=neither satisfactory nor unsatisfactory, 4=rather satisfactory, 5=very satisfactory. Thus, the mean score for attitude ranges from 1 to 5, with higher values reflecting a more positive attitude towards a participation in the NutriQuébec study.

The subjective norm will be calculated as the mean of three questions on a five point bipolar Likert scale. The three questions are: 1) The people most important to me might think that I should participate in the NutriQuébec study:1=very unlikely, 2=rather unlikely, 3=neither likely nor unlikely, 4=rather likely, 5=very likely; 2) Many people I know may be interested in participating in the NutriQuébec study: 1=very unlikely, 2=rather unlikely, 3=neither likely nor unlikely, 4=rather likely, 5=very likely; 3) If I participated in the NutriQuébec study, most people who are important to me could...: 1= strongly disapprove, 2= slightly disapprove, 3=neither approve nor disapprove, 4= slightly approve, 5=strongly approve. Thus, the mean score for the subjective norm ranges from 1 to 5, with higher values representing perceptions that important others expect the participant to participating in the NutriQuébec study.

The preferences about the recruitment in the NutriQuébec study will be assessed by a questionnaire. The question is: By which means of communication would advertising about the NutriQuébec study be most likely to capture your attention?: 1=Television, 2=Social networks (Facebook, Instagram, YouTube, etc.), 3=The Internet (other than social networks), 4=Newspapers, 5=Posters in public places (hospitals, community centres, etc.), 6=Flyers, 7=Postal mail, 8=None.