Table 1

 Correlation coefficients for the relationship of IQ at 7, 9 and 11 years with social and physical characteristics of study participants

IQ at 7 yearsIQ at 9 yearsIQ at 11 years
*Point biserial correlation coefficient.
†Higher scores on these variables indicates greater socioeconomic adversity.
For all correlation coefficients, p<0.001.
Birth weight
    r0.110.090.09
    n690568036813
Father’s social class in childhood†
    r−0.31−0.29−0.31
    n690568036813
Family size in childhood†
    r−0.24−0.21−0.24
    n689867746807
Housing tenure in childhood
    r0.240.230.22
    n687367746783
Car ownership in childhood
    rpb*0.170.150.15
    n686067606768
Educational attainment
    r0.520.560.61
    n681267116721
Income in adulthood
    r0.290.300.32
    n675666566667
Social class in adulthood†
    r−0.40−0.43−0.46
    n675266576672
Housing tenure in adulthood
    r0.230.220.24
    n689567936803
Car ownership in adulthood
    r0.210.190.19
    n689267906768