Trial design {8}
APC, APPENDIX
This study is a randomized-controlled parallel-group trial examining the effect of a short, animated storytelling video on knowledge and behavioral expectation to reduce dietary sodium intake. We will use an online academic research platform (Prolific Academic) to recruit and randomize 10,000 participants aged 18–59 years into four study groups.In group 1 (intervention group), participants will be shown a SAS video on dietary sodium (see multimedia Appendix) and thereafter be asked to complete a questionnaire to assess knowledge on dietary sodium and behavioral expectation.In group 2 (exposed control group), participants will be asked to complete a questionnaire to assess knowledge on dietary sodium and behavioral expectation (the same questionnaire as in group 1), however, without being exposed to the SAS video on dietary sodium before.In group 3 (attention placebo control group), participants will be shown an attention placebo control (APC) video, unrelated to the outcomes measured in this trial, before being asked to complete the knowledge and behavioral expectation questionnaire.Participants in group 4 (unexposed control group) will not view a video and will not be asked to complete the questionnaire.Two weeks later, participants in all four arms will once again be asked to complete the knowledge and behavioral expectation questionnaire. Figure Trial design