Table 2.
Sample characteristics by age group (n = 2897).
| 2nd grade (n = 1083) | 3rd grade (n = 1036) | 4th grade (n = 778) | |
|---|---|---|---|
| Age at session 1 (mean, SD) | 7.6 (0.32) | 8.7 (0.36) | 9.7 (0.35) |
| Sex (% girls) | 49.3 | 48.8 | 51.5 |
| MATERNAL EDUCATION (%) | |||
| Primary or low | 14.5 | 10.1 | 10.9 |
| Secondary | 23.6 | 26.1 | 32.8 |
| University | 56.9 | 56.9 | 50.3 |
| Missings | 5.0 | 7.0 | 6.0 |
| SES Vulnerability Index (%) | |||
| 1st tertile | 35.8 | 37.0 | 37.8 |
| 2nd tertile | 31.1 | 31.6 | 28.7 |
| 3rd tertile | 31.6 | 30.0 | 32.7 |
| Missings | 1.5 | 1.5 | 0.9 |
| ORIGIN (%) | |||
| Spanish | 82.7 | 83.4 | 85.2 |
| Other | 16.1 | 15.1 | 13.4 |
| Missings | 1.2 | 1.5 | 1.4 |
| LINGUISTIC CONTEXT (%) | |||
| Bilingual (Spanish and Catalan) | 12.4 | 13.2 | 11.3 |
| Catalan | 46.3 | 43.4 | 46.3 |
| Spanish | 27.6 | 29.1 | 31.5 |
| Other language | 8.8 | 7.4 | 5.0 |
| Missings | 5.0 | 6.9 | 5.9 |
| ADHD SUBTYPES (%) | |||
| No ADHD | 89.4 | 87.6 | 86.9 |
| ADHD-inattentive | 6.0 | 6.0 | 6.4 |
| ADHD-hyperactive/impulsive | 1.4 | 1.5 | 2.4 |
| ADHD-combined | 2.5 | 1.6 | 3.1 |
| Missings | 0.7 | 3.3 | 1.2 |
SES, socio-economic status; ADHD, Attention Deficit and Hyperactivity Disorder.