Criterion validity of a research-based application for tracking screen time on android and iOS smartphones and tablets

This study evaluated the criterion validity of a newly developed application for assessing smartphone use on iOS and Android based devices. A sample of adult Danes (n=40; 40% female; median age= 42.0 years) had the application SDU DeviceTracker installed on their mobile phone together with a commercial application that served as a reference for comparison (Apple Screen Time (iOS) or ActionDash (Android)). Each participant collected data for at least 6 days, adding up to a total of 277 assessment days. Day-level analyses were performed and Bland-Altman limits of agreement for repeated measurements and repeated measurement correlation was calculated. A non-significant mean bias of −0.8 min/day and a correlation coefficient of 0.99 (95% CI: 0.98 to 0.99) was observed for the assessment of screen time on Android devices compared to the reference method. For iOS devices a significant mean bias of 19.3 min/day and a correlation coefficient of r=0.88 (95% CI: 0.84 to 0.91) was observed. A correction method for systematic error in the assessment of screen time on iOS devices was provided. The study concluded that SDU DeviceTracker provides an opportunity to collect highly detailed and valid information about screen usage over extended periods of time.