Study Design
This study was conducted online between November and December 2019 using the Qualtrics survey platform. We used a 2×2×2 between-subjects factorial design (Video: yes, no × Questions: yes, no × health literacy: adequate, inadequate). We aimed to recruit equal numbers of participants with inadequate and adequate health literacy by oversampling participants who had less than a university degree level of education compared with those with a university degree level of education or greater (using a 70:30 ratio, respectively). However, this article reports on the intervention effects only; preplanned analyses related to the role of health literacy will be reported separately.