Table 3. Descriptives of confounders by frequency of cigarette use at age 16% (N).
| Cigarette frequency age 16 | Never 55.2 (988) | Experimenter 35.0 (627) | Weekly 4.3 (77) | Daily 5.5 (99) | P value |
|---|---|---|---|---|---|
| FH depression | 25.8 (255) | 28.9 (181) | 28.6 (22) | 34.4 (34) | 0.044 |
| FH schizophrenia | 0.9 (9) | 0.8 (5) | 0 | 1.0 (1) | 0.742 |
| Maternal education 1 | 74.8 (739) | 75.0 (470) | 79.2 (61) | 80.8 (80) | 0.189 |
| Urban dwelling | 88.7 (876) | 89.0 (558) | 90.9 (70) | 86.9 (86) | 0.925 |
| Gender (female) | 51.0 (504) | 67.5 (423) | 72.7 (56) | 64.7 (64) | <0.001 |
| Borderline personality 2 | 1.0 (10) | 1.6 (10) | 0 | 2.0 (2) | 0.467 |
| IQ at age 8 m(sd) | 109.9 (15.2) | 110.8 (15.3) | 108.6 (14.2) | 106.6 (16.7) | 0.199 |
| Psychotic experiences age 12 | 3.0 (30) | 4.2 (26) | 2.6 (2) | 6.1 (6) | 0.138 |
| Conduct disorder 3 | 5.3 (52) | 7.0 (44) | 9.1 (7) | 13.1 (13) | 0.001 |
| Peer problems | 7.6 (75) | 5.7 (36) | 1.3 (1) | 12.1 (12) | 0.661 |
| Bullied | 30.5 (301) | 30.0 (188) | 27.3 (21) | 31.3 (31) | 0.868 |
| Cannabis age 16 4 | 5.0 (49) | 47.2 (296) | 73.3 (58) | 88.9 (88) | <0.001 |
| Illicit drugs age 16 | 5.2 (51) | 22.5 (141) | 44.2 (34) | 63.6 (63) | <0.001 |
| Alcohol use age 16 5 | 15.3 (151) | 50.7 (318) | 67.5 (52) | 72.7 (73) | <0.001 |
1No higher education. Categorised like this for purposes of presentation in this table only.
2Defined as score of 4 or over, for the purposes of presentation in this table only.
3Early onset persistent group membership. Categorised like this for purposes of presentation in this table only.
4Ever used cannabis. Categorised like this for purposes of presentation in this table only.
5Hazardous alcohol use. Categorised like this for purposes of presentation in this table only.