Table 1.
Characteristics of the Discovery and Test Sets
| Discovery set | Test set | |||||
|---|---|---|---|---|---|---|
| Characteristics | N | % | Mean (SD) | N | % | Mean (SD) |
| Age in years at SRS | 6.10 (0.43) | 6.12 (0.42) | ||||
| Score per SRS item | 0.22 (0.23) | 0.23 (0.26) | ||||
| Boys | 1450 | 49.1 | 502 | 50.9 | ||
| Ethnicity child | ||||||
| Dutch | 2034 | 68.9 | 652 | 66.1 | ||
| Other western | 267 | 9.0 | 95 | 9.6 | ||
| Nonwestern | 653 | 22.1 | 239 | 24.2 | ||
| Gestational age | 39.93 (1.70) | 39.85 (1.88) | ||||
| Birth weight (g) | 3447 (559) | 3441 (572) | ||||
| Cohort | ||||||
| 2002 | 273 | 9.2 | 93 | 9.4 | ||
| 2003 | 837 | 28.3 | 283 | 28.7 | ||
| 2004 | 961 | 32.5 | 309 | 31.3 | ||
| 2005 | 871 | 29.5 | 297 | 30.1 | ||
| 2006 | 14 | 0.5 | 4 | 0.4 | ||
| Maternal education | 971 | |||||
| Lower | 134 | 4.6 | 58 | 6.0 | ||
| Middle | 1040 | 35.9 | 346 | 35.6 | ||
| Higher | 1722 | 59.5 | 567 | 58.4 | ||
| Maternal age | 31.36 (4.46) | 31.54 (4.42) | ||||
| Parity number | ||||||
| 0 | 1801 | 61.0 | 594 | 60.4 | ||
| 1 | 867 | 29.4 | 276 | 28.0 | ||
| 2+ | 284 | 9.6 | 114 | 11.6 | ||
SRS: Social Responsiveness Scale.