Table 1.
Sample demographics by sample included versus not included
| Not included n = 1139 | Included n = 771 | P value | |
|---|---|---|---|
| Female sex, n (%) | 549 (48.2) | 396 (51.4) | 0.18 |
| Expressive language score at age 4, M (SD) | 96.5 (15.2) | 102.8 (14.4) | < 0.001 |
| Receptive language score at age 4, M (SD) | 93.7 (15.0) | 99.9 (14.1) | < 0.001 |
| Expressive language score at age 5, M (SD) | 98.7 (13.7) | 101.2 (13.9) | 0.02 |
| Receptive language score at age 5, M (SD) | 96.1 (14.2) | 100.3 (14.0) | < 0.001 |
| Expressive language score at age 7, M (SD) | 96.4 (13.6) | 100.1 (13.4) | < 0.001 |
| Receptive language score at age 7, M (SD) | 91.9 (14.5) | 95.6 (13.3) | < 0.001 |
| Non-verbal intelligence at age 4, M (SD) | 102.3 (13.8) | 106.1 (12.6) | < 0.001 |
| Non-verbal intelligence at age 7, M (SD) | 102.8 (14.6) | 105.9 (14.7) | < 0.001 |
| English spoken at home, n (%) | 1045 (91.8) | 753 (97.7) | < 0.001 |
| Family history of communication problems, n (%) | 0.80 | ||
| No problem | 856 (75.2) | 579 (75.1) | |
| Speech/language problems | 225 (19.8) | 146 (18.9) | |
| Stuttering problem | 58 (5.1) | 46 (6.0) | |
| Maternal mental health (K6), M (SD) | 3.5 (3.3) | 3.4 (3.1) | 0.76 |
| Maternal education level at baseline, n (%) | < 0.001 | ||
| Did not complete high school | 298 (26.3) | 149 (19.3) | |
| Completed high school | 482 (42.5) | 283 (36.7) | |
| University degree or higher | 354 (31.2) | 339 (44.0) | |
| Maternal age at baseline, M (SD) | 31.4 (4.7) | 32.5 (4.2) | < 0.001 |
| SEIFA disadvantage score at baseline, M (SD) | 1029.8 (64.9) | 1045.3 (52.7) | < 0.001 |