The effect of demographic variables on the assessment of cognitive ability

This study examines the effect of parental educational levels, sex, and family structure on the WISC-V Full Scale IQ (FSIQ) and primary index scores (VCI, VSI, FRI, WMI, and PSI) in a representative sample of children from Spain ( N = 1008).

Differences between demographic groups were examined using independent-samples t-test , ANOVA and Hochberg post hoc tests. A multiple regression analysis was performed to examine whether demographic variables could predict children’s FSIQ score.

Results showed that the parents’ educational level was a significant predictor of children’s FSIQ and significant increases in mean FSIQ and primary index scores were found as the parents’ educational level increased. Sex was not a significant predictor of children’s FSIQ but slight sex differences were found for PSI. The family structure was a significant predictor of FSIQ but its contribution to the global model was small. Children from two-parent families obtained higher FSIQ, VCI, VSI, and FRI mean scores than children from single parent families.

The results support the design of a normative sample stratified by demographic variables. Parental education levels, as a good predictor of children’s FSIQ score, must be taken into account as a key stratification variable.