Maartje Boer

VALIDATION OF THE SMD-SCALE 39 2 Figure 2.1 Distribution of the Number of Endorsed Problematic SMU Criteria, n = 6,609 Notes. SMU = social media use. The number of endorsed problematic SMU criteria was measured with the nine- item Social Media Disorder-Scale. Likelihood estimation. All analyses were conducted with the sample weight and with a cluster correction on school-class level to correct for the nested structure of the data. All syntax files are publicly available and may be consulted via https://osf.io/pngw5/. Results Structural Validity Table 2.1 shows that the EFA on the calibration sample identified one factor with an eigenvalue higher than one (4.572), suggesting a one-factor solution. The parallel analysis showed that only the empirical eigenvalue of the first factor exceeded its 95 th random data eigenvalue, which also supports a one- factor solution. Although the model fits of the one-factor (CFI = 0.984; TLI = 0.979; RMSEA = 0.029; SRMR = 0.049), two-factor (CFI = 0.994; TLI = 0.989; RMSEA = 0.021; SRMR= 0.034), and three-factor (CFI = 1.000; TLI = 1.000; RMSEA < 0.001; SRMR=