Table 1 Descriptions of main variables and other related variables (N = 2872)

 Bullying role: Bullies

256 (9.5)

 Victims

218 (7.6)

 Bully-victims

106 (2.9)

 Bystanders

2,292 (80.0)

 Defending behaviors score (range: 1–5)

1.82 (0.03)^a

 Social anxiety score (range: 1–3)

1.63 (0.01)^a

 Depressive symptoms score (range:1–3)

1.65 (0.01)^a

 Sex: Girl

1,430 (49.4)

  Boy

1,442 (50.6)

 Grade: 7

899 (31.7)

  8

994 (33.4)

  9

979 (34.9)

 Aggressive tendency score (range: 1–5)

2.43 (0.03)^a

 Communication skills score (range: 1–4)

2.87 (0.02)^a

 Parents’ marital status: Not married

567 (18.2)

  Married

2,305 (81.8)

 Parents’ education: Junior high school

450 (13.4)

  Senior high school

1,664 (60.6)

  College/University

500 (17.5)

  Unknown

258 (8.5)

 Family activities score (range:1–5)

2.89 (0.03)^a

 Family support score (range: 1–5)

3.12 (0.03)^a

 Family conflict score (range: 1–5)

1.73 (0.02)^a

 Punishment score (range: 1–5)

1.70 (0.02)^a