Table 2

Characteristics of those who participated in either a WALNA or NAPLAN test between 1989 and 2007 (n=45 697 children) for exposed and comparison cohorts by Indigenous status

Variable Non-IndigenousIndigenous
Exposed (n=7804)Comparison (n=22 107)Exposed (n=4887)Comparison (n=10 899)
Frequency matching variables%%%%
Maternal age
 <20 years12.412.625.224.4
 20–24 years29.529.334.334.2
 25–29 years29.228.823.624.2
 30+ years28.929.216.917.2
Child’s year of birth
 1989–199334.634.336.434.6
 1994–199836.535.636.035.5
 1999–200329.030.027.630.0
Maternal characteristics during pregnancy
Marital status
 Married73.785.860.066.5
 Never married22.813.437.531.5
 Separated/divorced/widowed3.10.81.91.6
 Missing*0.30.10.60.4
SEIFA – area of residence
  Most disadvantaged >10%3.76.50.20.5
 10 to <25%8.912.01.01.8
 25 to <50%18.622.45.07.4
 50 to <75%25.324.713.517.3
 75 to <90%19.615.819.021.6
  Most disadvantaged 10%15.89.929.630.3
 Missing*8.28.631.721.0
Health service region
 Perth metro71.772.332.234.0
 Rural/remote28.327.767.866.0
Illicit drug use record39.41.725.35.4
Mental disorder (other than substance use)53.39.132.912.6
Maternal smoking51.822.266.644.3
Parity
 038.849.223.728.9
 130.331.421.824.0
 217.613.119.618.5
 3+13.36.234.828.5
Child characteristics
Male49.149.149.948.7
Low birth weight (<2500 g)*9.85.417.79.5
Preterm (gestational age <37 weeks)9.76.016.310.2
School achievement
Number of tests (observations)21 38560 71611 06127 002
Mean number of tests2.742.752.262.48
  • Note: Maternal smoking is restricted to birth years from 1998 onwards (n=17 631).

  • *117 missing cases for marital groups; 3 missing cases for birth weight; 6379 missing cases for SEIFA.

  • NAPLAN, National Assessment Program – Literacy and Numeracy; SEIFA, Socio-Economic Index for Areas; WALNA, Western Australian Literacy and Numeracy Assessment.