Table 1 Description of studies included in SET-Bullying

Schedule of study measurements^a

 T1: Baseline, May 2002, −3 months

 T2: End of intervention, May 2003, 9 months

 T3: Follow-up 1, May 2004, 21 months

 T4: Follow-up 2, May 2005, 33 months

T1: Baseline, late November/early December 1990, −9 months

T2: End of intervention, late November/early December 1992, 15 months

T3: Follow-up, late November/early December 1993, 27 months

School grades (age in years) of pupils

 Primary school: 5–7th (age: 11–13)

Primary school: 3–6th (age: 7–11)

 Secondary school: 8–10th (age: 14–16)

Secondary school: 7–18th (age: 12–18)

Number and type of study groups/clusters

 18 primary school grade groups

17 primary school groups

 6 secondary school grade groups

7 secondary school groups

Number of pupils at each study measurement^b

 Primary school: T1: 417, T2: 414, T3: 413, T4: 414

Primary school: T1: 2617, T2: 2481, T3: 655

 Secondary school: T1: 329, T2: 354, T3: 364, T4: 365

Secondary school: T1: 4123, T2: 4624

Number (percentage) of female pupils in each measurement^b

 Primary school: T1: 228 (54.7 %), T2: 222 (53.6 %), T3: 199 (48.2 %), T4: 210 (50.7 %)

Primary school: T1: 1350 (51.6 %), T2: 1234 (49.7 %), T3: 317 (48.4 %)

 Secondary school: T1: 178 (54.1 %), T2: 194 (54.8 %), T3: 166 (45.6 %), T4: 170 (46.6 %)

Secondary school: T1: 1977 (48.0 %), T2: 2272 (49.1 %)