In the validation sample (n = 723), the mean Internalizing Scale score was 1.32 (SD = 2.36, Q1 = 0, median = 0, Q3 = 2, range = [0, 19], Figure 1). Descriptive statistics were similar in the development sample. Age-group-specific descriptive statistics of scale scores are presented in Table 1. We examined all the results that follow in adolescents and adults, unless otherwise stated. Results in each age group were similar to the pooled ones presented.
