(In)accuracy and Convergent Validity of Daily End-of-day and Single-time Self-reported Estimations of Smartphone Use among Adolescents

Understanding the measurement inaccuracy and bias introduced by self-reports of smartphone use is essential for making meaningful inferences about smartphone use and its effects. Evidence for the self-reports of smartphone use in intensive longitudinal studies is largely missing. Based on self-reported and digital trace data from 137 Czech adolescents (41% girls, Mage = 14.95 years), this study examined the accuracy, directional bias, and convergent validity of daily end-of-day and single-time reports of screen time and phone-checking behavior. Overall, the study found considerable discrepancies between self-reported smartphone use and digital trace and low between-person convergent validity for all self-reports considered for the study. Respondents usually reported shorter screen time and lower frequency of phone-checking behavior as compared to digital trace, both in daily and single-time self-reports. The within-person convergent validity between daily reports and digital tracking was low, indicating poor self-reports ability to capture the actual day-to-day fluctuations in smartphone use. This study adds to the existing evidence showing that self-reports based insights into how people use smartphones differ considerably from digital trace data and shows that both person and situational levels contribute to explaining the discrepancy between digital trace and self-report data among adolescents.