Maartje Boer

SUMMARY AND DISCUSSION 313 9 spent on (social media) applications and not always guarantee protection of private data. Furthermore, the knowledge of being tracked may influence usage behaviors of adolescents. As highlighted above, to understand the possible effects of SMU, it may be more informative for future research to focus on specific positive and negative experiences on or related to social media (e.g., social interaction with peers, encountered online content, SMU problems), instead of on improving the measurement of and testing the effect of tracked SMU activities on wellbeing. After all, time spent on SMU is not an indicator of adolescents’ online experiences (Griffioen et al., 2021). Fifth, weuseddifferent conceptualizations of SMU intensity inour studies. In our cross-sectional study (Chapters 3, 4), SMU intensity was indicated by the frequency of online communication on social media, which is a more active SMU activity because it involves social interaction. In our longitudinal study (Chapters 5-7), SMU intensity was a composite measure of different SMU activities, such as direct messaging with peers as well as browsing social network sites. As such, conclusions about the associations with SMU intensity should be interpreted in light of the respective operationalizations. However, it should be mentioned that the consequences of using different operationalizations of SMU intensity may be limited, given that our findings suggested that different SMU activities, ranging from active to more passive, do not yield different associations with wellbeing (Chapter 8), which was also supported by other researchers (Valkenburg, Van Driel, et al., 2021). Furthermore, with both operationalizations of SMU intensity, we observed comparable results, whereby rather problematic SMU related negatively to wellbeing than the intensity of SMU. Conclusion This dissertation highlights the differences between two SMU behaviors, namely the intensity of SMU, indicated by the frequency of SMU, and SMU problems, indicated by addiction symptoms related to social media. This distinction is important for understanding the relation between SMU and adolescent wellbeing, because, in general, not the intensity of SMU, but SMU problems were negatively related to wellbeing. This finding informs those concernedwith thewellbeing of adolescents that rather SMUproblems are an indication of harmful SMU than high intensity of SMU. High intensity of SMU