Abstract
A growing number of studies have tried to assess the effects of social media on adolescents, who are among the most avid social media users. To establish the effects of social media use, we need accurate and valid instruments to measure adolescents' time spent with these media. The aim of this preregistered study was to examine the accuracy and convergent validity of retrospective surveys and experience sampling method (ESM) surveys, by comparing adolescents' responses to these self-report measures with their digital trace data. The sample consisted of 125 adolescents (48% girls; Mage = 14.1) with Android smartphones. In both retrospective surveys and ESM, adolescents overestimated their time spent on social media. They more accurately estimated their time spent on platforms that are used in a less fragmented way (Instagram) than on platforms that are used in a more fragmented way (Snapchat). The between-person convergent validity of adolescents’ time estimates according to retrospective surveys and ESM reached the threshold for minimum acceptable convergent validity (r ranged from .55 to .65). The within-person convergent validity of adolescents' ESM estimates of their time spent on social media was unacceptable (r = .32). The between- and within-person convergent validity of ESM estimates decreased over time (i.e., fatigue effect).
