Table 1. Robust regression of age-related behavioural differences.

Variable	Estimate	s.e.	Test statistic	P-value
Fluid intelligence and age
Age	−0.034	0.002	t-value	<2e−16
			−21.070
Age (robust sandwich)	−0.037	0.002	z-value	<2e−16
			−20.831
Multitasking and age
Age	−0.014	0.002	t-value	<1.66e−11
			−6.874
Age (robust sandwich)	−0.018	0.002	z-value	<4.46e−11
			−6.588

Robust regression using heteroscedasticity consistent sandwich estimator to regress cognitive factor scores on age. Results show highly similar results for robust and regular regression, suggesting that the increase in behavioural variance with age does not affect our estimate of age-related differences in the two cognitive factors.

P values for the robust regression are computed using a heteroscedasticity-consistent robust sandwich estimator.