Pre

Post

Change

Factor (Cronbach’s α)

Group

Mean (SD)

Mean (SD)

Mean (SD)

P**

Effect size

P‡

Concentration of attention (0.91)

Intervention

46.9 (12.2)

53.5 (12.0)

6.6 (9.6)

<0.001

0.55

<0.001

Control

48.2 (13.3)

52.2 (13.0)

4 (9.1)

<0.001

0.31

P*

0.100

0.700

Verbal/physical aggressiveness control (0.91)

Intervention

73.5 (17.3)

81.9 (15.6)

8.4 (13.9)

<0.001

0.51

<0.001

Control

75.3 (16.9)

79.2 (15.4)

3.9 (13.5)

<0.001

0.24

P*

0.175

0.287

Friendship skills (0.92)

Intervention

44.8 (10.4)

49.2 (9.9)

4.4 (8.2)

<0.001

0.43

0.235

Control

45 (11.3)

48.9 (9.9)

3.9 (8)

<0.001

0.37

P*

0.706

0.574

Empathy (0.89)

Intervention

31.7 (8.5)

38.1 (8.3)

6.4 (7.9)

<0.001

0.76

<0.001

Control

32.6 (7.8)

36.2 (8.5)

3.5 (8.0)

<0.001

0.43

P*

0.138

<0.001

Participation

/cooperation in class (0.90)

Intervention

50 (11.5)

56.1 (11.2)

6.1 (9.6)

<0.001

0.54

<0.001

Control

51.3 (12.0)

55.4 (12.1)

4.1 (9.3)

<0.001

0.34

P*

0.117

0.023

Emotions’ identification

and management (0.91)

Intervention

64.6 (15.0)

74.8 (15.8)

10.1 (13.2)

<0.001

0.66

<0.001

Control

66.6 (17.5)

71.6 (16.5)

5.1 (13.5)

<0.001

0.30

P*

0.153

0.007

Victimization control (0.87)

Intervention

28.7 (6.4)

30.5 (6.0)

1.8 (5.2)

<0.001

0.28

0.011

Control

29.4 (5.1)

30.4 (5.0)

1.0 (5.0)

0.034

0.20

P*

0.095

0.586

Problem solving (0.92)

Intervention

29.9 (9.0)

36 (9.0)

6.1 (7.3)

<0.001

0.68

<0.001

Control

30.7 (9.7)

34.1 (9.5)

3.4 (8.3)

<0.001

0.36

P*

0.197

<0.001

Self-esteem (0.92)

Intervention

52.2 (11.7)

60 (12.1)

7.8 (9.2)

<0.001

0.66

0.001

Control

53.2 (11.0)

60.1 (12.0)

6.9 (8.9)

<0.001

0.60

P*

0.262

0.139