Maartje Boer

VALIDATION OF THE SMD-SCALE 55 2 of adolescents’ self-reports. Fifth, because the data provided one scale that measured problematic SMU, comparison of the psychometric performance of alternative scales was not possible. The SMD-scale distinguishes itself from other scales, such as the BSMAS (Andreassen et al., 2016), by adding the criteria displacement, problems, and deception on top of the six core criteria of addiction. Statistical comparisons of different scales allow researchers to evaluate whether the three additional criteria substantially improve the conceptualization of problematic SMU. Sixth, the criterion validity assessment was limited to measurements related to adolescents’ wellbeing. Future studies examining the association between adolescents’ intensity of SMU activities and scores on the SMD-scale would extend current knowledge on the validity of the scale. In doing so, the use of objective measures of SMU activities collected through, for example, logged social media data (Marengo et al., 2020; Marino et al., 2017), is considered promising. Conclusion The present study has demonstrated that the SMD-scale has good psychometric properties. Given its solid factor structure, adequate test score reliability, and good validity of the test score interpretations, the scale is suitable for empirical assessments of problematic SMU among adolescents. The scale thereby facilitates future research on adolescent problematic SMU.