2) VAS scores of seven features. To verify the concurrent
validity of the seven subscales of the first SAS, the VAS scores of
seven features were added in the questionnaire. This scale was
added to determine the subjective thoughts of the participants
regarding the seriousness of their addiction. Each feature was
described above. Each item was assigned 1–10 points. The Visual
Analogue Scale is shown in Figure S1.
3) K-scale. K-scale was added to verify the concurrent
validity of SAS. K-scale was developed through the collaborative
effort of Korea Agency for Digital Opportunities and Seoul
National University. It was revised from Kimberly Young’s scale
of 20 questions into a 40-item, 4-point scale [14]. In this study, the
internal-consistency test result (Cronbach’s alpha) of K-scale was
0.95.