Primary Outcome Measure
The primary outcome of this study was the average screen time per day of the child, obtained using the SCREENS questionnaire [The use of four types of devices at home was considered as screen time: (1) television (including DVD, video games, PlayStation, and Xbox), (2) computers (desktop, laptop, and Chromebook), (3) telephones and smartphones, and (4) other mobile devices (tablets, iPad, and Nintendo Switch). For each device type, the weekday and weekend use times were averaged to obtain the device-specific screen time in hours per day, that is, ([total weekday × 5] + [total weekend day × 2]) / 7. The total screen time per day was calculated as the sum of use time for all 4 types of devices. To ensure the fidelity of the primary outcome in the questionnaire, the self-reported use time was cross-checked with screenshots of the screen media diary among 10% (18/180) of the participants. The request for the diary was made only after the completion of the final questionnaire. There was an agreement of 83% (15/18) between the reported time in the questionnaire and that in the diary.