Maartje Boer

INTRODUCTION 23 1 Table 1.1 Chapter Overview With Sample Information Chapter Title Sample Sample characteristics Sample size 2 Validation of the Social Media Disorder-Scale in adolescents: Findings from a large-scale nationally representative sample HBSC Netherlands, cross-sectional, 2017 Age = 12-16 M = 13.9 SD = 1.4 6,626 3 Cross-national validation of the Social Media Disorder-scale: Findings from adolescents from 44 countries HBSC international, cross-sectional, 2017/2018 Age = 11, 13, and 15 M = 13.5 SD = 1.6 222,532 adolescents from 44 countries 4 Adolescents' intense and problematic social media use and their wellbeing in 29 countries HBSC international, cross-sectional, 2017/2018 Age = 11, 13, and 15 M = 13.5 SD = 1.6 154,981 adolescents from 29 countries 5 Attention deficit hyperactivity disorder-symptoms, social media use intensity, and social media use problems in adolescents: Investigating directionality DiYo, longitudinal, 3 waves, 2015-2017 Age (T1) = 11-15 M = 12.9 SD = 0.7 543 6 Social media use intensity, social media use problems, and mental health among adolescents: Investigating directionality and mediating processes DiYo, longitudinal, 3 waves, 2016-2018 Age (T1) = 10-16 M = 13.1 SD = 0.8 2,109 7 The course of problematic social media use in young adolescents: A latent class growth analysis DiYo, longitudinal, 4 waves, 2015-2019 Age (T1) = 11-15 M = 12.5 SD = 0.6 1,419 8 The complex association between social media use intensity and adolescent wellbeing: A longitudinal investigation of five factors that may affect the association DiYo, longitudinal, 4 waves, 2015-2019 Age (T1) = 11-15 M = 12.5 SD = 0.6 1,419 9 Summary and discussion subsets of the data. The subset selection depended on the availability of data at time of the manuscript preparation and different subsample selections, which yielded longitudinal samples ranging from 543 to 2,109 adolescents. More details regarding the sample characteristics are provided in Table 1.1.