| Wave 1 | Waves 2 and 3 | ||||||
---|---|---|---|---|---|---|---|---|
 | N | Precourse | Postcourse | Effect | N | Precourse | Postcourse | Effect |
(Mean, SD) | (Mean, SD) | size | (Mean, SD) | (Mean, SD) | size | |||
Emotional symptoms | 1067 | 3.8 | 2.8 | - 0.42 | 3154 | 3.8 | 2.9 | - 0.37 |
 |  | (2.5) | (2.3) |  |  | (2.6) | (2.5) |  |
Conduct problems | 1071 | 4.3 | 3.1 | - 0.55 | 3144 | 4.4 | 3.4 | - 0.45 |
 |  | (2.4) | (2.2) |  |  | (2.5) | (2.3) |  |
Hyperactivity | 1053 | 6.2 | 5.0 | - 0.43 | 3138 | 6.2 | 5.3 | - 0.34 |
 |  | (2.7) | (2.6) |  |  | (2.7) | (2.7) |  |
Peer problems | 1064 | 3.3 | 2.8 | - 0.24 | 3131 | 3.3 | 3.0 | - 0.15 |
 |  | (2.2) | (2.1) |  |  | (2.3) | (2.2) |  |
Prosocial | 1068 | 6.4 | 7.0 | - 0.26 | 3165 | 6.4 | 6.9 | 0.22 |
 |  | (2.3) | (2.1) |  |  | (2.3) | (2.2) |  |
Total difficulties | 1038 | 17.5 | 13.5 | - 0.57 | 3028 | 17.8 | 14.5 | - 0.45 |
 |  | (6.9) | (7.0) |  |  | (7.2) | (7.4) |  |
Impact | 1031 | 2.9 | 1.7 | - 0.48 | 3046 | 3.0 | 1.7 | - 0.52 |
 |  | (2.7) | (2.4) |  |  | (2.8) | (2.4) |  |