**3. STUDY 2—the HBSC study**

#### **3.1 Methods**

#### *3.1.1 Procedures*

The HBSC study network integrated multiple countries in 2018 and 2022. In 2018, 44 countries participated; in 2022, 51 countries participated [22–24]. Participants constitute a representative sample for the school grades under study. Schools and classes were picked at random from a national list. All ethical procedures and permissions were in place, and participation was both anonymous and voluntary. Questionnaires were administered online. Full details with the final national report of the HBSC study in 2018 [22] and 2022 [23].

#### *3.1.2 Participants*

In 2018, 8215 pupils from the 6th (30.7%), 8th (33.7%), 10th (20.8%), and 12th (14.8%) grades participated, with 52.7% being female and a mean age of 14.36 (SD = 2.28). In 2022, 7649 pupils from the 6th (22.4%), 8th (25.4%), 10th (28.1%), and 12th (24.1%) grades responded, with 51.8% being female and a mean age of 15.05 (SD = 2.36). Therefore, considering the 2018 and 2022 HBSC studies, 15,750 pupils were included, 51.8% from the 2018 HBSC study wave and 48.2% from the HBSC 2022 wave, and 53.2% were female.

#### **3.2 Instruments**

The measures and variables under study are described in **Table 3**.

#### **3.3 Statistical analysis and main results**

Two groups were created from the measurement of life satisfaction (low—45.4%; high—54.6%), and two groups were created from the evaluation of psychological symptoms (reduced—47.5%; and pronounced—52.5%). In both variables, the median was used as a cut-off point). Four groups were obtained from the combination of the four situations: (1) *Complete Psychological Health*—high life satisfaction and low psychological symptoms (33.4%); (2) *Incomplete Psychological Health*—low life satisfaction and low psychological symptoms (14.1%); (3) *Incomplete Psychological* 


#### **Table 3.**

*Measures and variables under study.*

*Distress*—high life satisfaction and pronounced psychological symptoms (21.2%); (4) *Complete Psychological Distress*—low life satisfaction and pronounced psychological symptoms (31.3%).

It was confirmed, as in the previous DGEEC 2022 study, that in the HBSC study (either in 2018 or in 2022), younger pupils and boys were significantly more frequent in the group of complete psychological health and older pupils and girls were significantly more frequent in the group of complete psychological distress. There was also an age/grade gradient, with the situation deteriorating as schooling progresses.
