Maartje Boer

SMU AND WELLBEING ACROSS COUNTRIES 125 4 Table A4.1 Multilevel Unstandardized Results (n individuals = 154,981, n countries = 2 9) Mental wellbeing School wellbeing Social wellbeing M1 d Life satisfaction M2 d Psychological complaints M3 c School satisfaction M4 c School pressure M5 g Family support M6 g Friends support WITHIN B (SE) B (SE) B (SE) B (SE) B (SE) B (SE) Intense SMU 0.023 (0.015) 0.110*** (0.012) -0.064*** (0.010) 0.055*** (0.010) 0.039* (0.016) 0.327*** (0.019) Problematic SMU -0.823*** (0.038) 0.619*** (0.024) -0.316*** (0.017) 0.292*** (0.021) -0.619*** (0.027) -0.343*** (0.026) CROSS-LEVEL B (SE) B (SE) B (SE) B (SE) B (SE) B (SE) Intense SMU × intense SMU prevalence 1.229*** (0.271) -0.533** (0.171) 0.816*** (0.234) 0.786*** (0.218) Intense SMU × problematic SMU prevalence 0.947 (0.607) 1.107* (0.526) Problematic SMU × intense SMU prevalence -0.422 (0.380) -0.460 (0.338) Problematic SMU × problematic SMU prevalence 2.183* (0.977) 2.839* (1.118) MODEL FIT Estimate Estimate Estimate Estimate Estimate Estimate Free parameters 1 23 23 22 22 26 26 AIC 616002.8 430723.3 383745.5 399546.0 597158.6 597480.0 BIC 616231.7 430952.2 383964.4 399764.9 597417.4 597738.8 RANDOM PARAMETERS Estimate (SE) Estimate (SE) Estimate (SE) Estimate (SE) Estimate (SE) Estimate (SE) Variance between individuals 3.117*** (0.079) 0.943*** (0.020) 0.696*** (0.022) 0.771*** (0.023) 2.759*** (0.234) 2.765*** (0.167) Variance between countries 0.021*** (0.006) 0.021*** (0.006) 0.024** (0.008) 0.035* (0.014) 0.136*** (0.030) 0.174*** (0.043) (Residual) variance intense SMU 0.002 (0.001) 0.003** (0.001) 0.002** (0.001) 0.002* (0.001) 0.003* (0.002) 0.006 (0.003) (Residual) variance problematic SMU 0.034** (0.011) 0.013* (0.006) 0.007** (0.002) 0.012 (0.008) 0.009* (0.004) 0.006 (0.003) 95% PI intense SMU 2 [-0.172 / 0.220] [-0.030 / 0.248] [-0.152 / 0.024] [-0.033 / 0.143] [-0.145 / 0.227] [0.115 / 0.545] 95% PI problematic SMU 2 [-1.179 / -0.467] [0.396 / 0.842] [-0.480 / -0.152] [0.077 / 0.507] [-0.826 / -0.396] [-0.516 / -0.144] R 2 random slope intense SMU 80.00% 40.00% 55.56% 41.67% + 8.33% R 2 random slope problematic SMU 25.00% 33.33% Notes. SMU = social media use; M = model; PI = prediction interval; R 2 = explained variance. 1 Parameters not shown in table (16): control variables female, family affluence, and age, the random intercept of the respective wellbeing indicator, effects of the country-level prevalence of intense and problematic SMU on the random intercept, the covariances between the random intercept and the random slopes, effects of country-level costs of mobile broadband and internet speed on country-level prevalence of intense and problematic SMU, the intercepts of the country-level prevalence of intense and problematic SMU, and the residual variances of the country-level prevalence of intense and problematic SMU. 2 Based on B 's and variance parameters of models without cross-level effects (Table 4.2, M1-6 c ). * p < 0.05; ** p < 0.01; *** p < 0.001.