Study cohorts: sample sizes, age range and instruments by time of measurement
| Time 1: Early childhood | Time 2: Middle childhood | Time 2: Adolescence | |||||||
| Round | N | Age (months) | Instrument* | Age (years;months) | Instrument† | Age (years;months) | Instrument† | Type of study | |
| Bangladesh16 | 1 | 1862 | 18 | Bayley-II | 5;3–5;8 | WPPSI | Program evaluation | ||
| Brazil 17 | 1‡ | 644 | 3 | Denver-II | 18;6 | WAIS | Birth cohort | ||
| 2 | 1412 | 6 | Denver-II | ||||||
| 3 | 1362 | 12 | Denver-II | ||||||
| Brazil 28 | 1‡ | 3907 | 12 | BDI-2 | Birth cohort | ||||
| 2‡ | 3869 | 24 | BDI-2 | ||||||
| Chile 117 | 1 | 128 | 6 | Bayley-I | 5;6–5;8 | WPPSI | Program evaluation | ||
| 2 | 1732 | 12 | Bayley-I | ||||||
| 3 | 279 | 18 | Bayley-I | ||||||
| Chile 29 | 1‡ | 4869 | 7–23 | BDI-2 | Birth cohort | ||||
| 1§ | 9201 | 24–58 | Tepsi | 4;1–6;2 | TVIP | ||||
| China18 | 1 | 990 | 18 | Bayley-III | Program evaluation | ||||
| Colombia 119 42 | 1 | 704 | 12–24 | Bayley-III | 4;6–5;8 | TVIP | Program evaluation | ||
| 2 | 631 | 24–42 | Bayley-III | ||||||
| Colombia 215 | 1 | 1311 | 6–42 | Bayley-III | 6;0–8;11 | WISC-V, TVIP | Instrument validation | ||
| 1 | 658 | 6–42 | Denver-II | ||||||
| 1 | 658 | 6–42 | ASQ-3 | ||||||
| 1‡ | 635 | 6–42 | BDI-2 Screener | ||||||
| Ecuador20 | 1 | 667 | 0–35 | Barrera | 5;7–8;8 | TVIP | 9;2–12;2 | TVIP | Program evaluation |
| Ethiopia10 11 | 1 | 193 | 12 | Bayley-III | 9;10–10;10 | PPVT | Birth cohort | ||
| 2 | 440 | 30 | Bayley-III | ||||||
| 3 | 456 | 42 | Bayley-III | ||||||
| Jamaica 121 | 1 | 225 | 15 | Griffiths | 6;6–7;1 | WPPSI, PPVT | Program evaluation | ||
| 2 | 218 | 24 | Griffiths | ||||||
| Jamaica 222 | 1 | 159 | 9–24 | Griffiths | 7;0–8;3 | SB-4, Raven’s, PPVT | 16;9–18;0 | WAIS | Program evaluation |
| 2 | 159 | 21–36 | Griffiths | ||||||
| 3 | 159 | 33–48 | Griffiths | ||||||
| Madagascar23 | 1 | 205 | 34–42 | SB-5 | 6;10–7;10 | SB-5, PPVT | Program evaluation | ||
| Netherlands 114 | 1 | 1985 | 1 | DDI | 4;7–6;1 | UKKI | Instrument validation | ||
| 2 | 1807 | 2 | DDI | ||||||
| 3 | 1963 | 3 | DDI | ||||||
| 4 | 1919 | 6 | DDI | ||||||
| 5 | 1881 | 9 | DDI | ||||||
| 6 | 1802 | 12 | DDI | ||||||
| 7 | 1776 | 15 | DDI | ||||||
| 8 | 1787 | 18 | DDI | ||||||
| 9 | 1815 | 24 | DDI | ||||||
| Netherlands 212 | 1 | 1016 | 24 | DDI | Birth cohort | ||||
| 2 | 995 | 30 | DDI | ||||||
| 3 | 1592 | 36 | DDI | ||||||
| 4 | 1534 | 42 | DDI | ||||||
| 5 | 1034 | 48 | DDI | ||||||
| South Africa13 | 1 | 485 | 6 | Bayley-I, Griffiths | 4;10–5;6 7;0–8;6 | Denver-II Raven’s (Coloured) | Birth cohort | ||
| 2 | 275 | 12 | Bayley-I, Griffiths | ||||||
| 3 | 1802 | 24 | Vineland | ||||||
| 4ठ| 1614 | 48 | Vineland | ||||||
*Early childhood testing instruments were the ASQ-3; Barrera; BDI-2 and BDI-2 Screener; Bayley-I, II and III; Denver-II, DDI; Griffiths; SB-5; Tepsi; and the Vineland. References for instruments are included with online supplementary appendix table A1.
†Middle childhood and adolescence testing instruments were the Denver-II; PPVT and the Spanish version, TVIP; Raven’s and Raven’s (Coloured); SB-4 and SB-5; UKKI; WAIS; WISC-V; and WPPSI. References for instruments are included with online supplementary appendix table A1.
‡These rounds of data that were not used in the final 565-item D-score model.
§Excludes children>48 months at Time 1 from validity tests.
ASQ-3, Ages & Stages Questionnaires; Barrera, Barrera Moncada; Bayley-I, II and III, Bayley Scales for Infant and Toddler Development; BDI-2, Battelle Development Inventory and Screener-2; DDI, Van Wiechenschema, referred to as the Dutch Developmental Instrument; Denver-II, Denver Developmental Screening Test; D-Score, Developmental Score; Griffiths, Griffiths Mental Development Scales; PPVT, Peabody Picture Vocabulary Test; Raven's, Raven's Progressive Matrices; SB-4 and SB-5, Stanford Binet Intelligence Scales; Tepsi, Test de Desarrollo Psicomotor; TVIP, Test de Vocabulario en Imagenes Peabody; UKKI, Utrechtse Korte Kleuter Intelligentietest; Vineland, Vineland Social Maturity Scale; WAIS, Wechsler Adult Intelligence Scale; WISC-V, Wechsler Intelligence Scale for Children - Revised; WPPSI, Wechsler Preschool and Primary Scale of Intelligence.