Table 2.

Parameter Estimates for the Ten Individual Task Measures and the Combined Score

	Meana	Variancea	Heritabilityb(p Value)	Proportion of Variance Explainedc
Executive/cognitive tasks
Stop task	−0.264	0.784	0.235 (0.061)	0.302
Shifting attentional set	−0.255	0.881	0.236 (0.091)	0.185
Time test	−0.369	0.830	0.583 (3.1 × 10−4)	0.207
Visuo-spatial sequencing	0.256	0.845	0.497 (0.001)	0.410
Digit span	0.249	0.878	0.235 (0.076)	0.338
Motor tasks
Pursuit	−0.075	0.905	0.567 (6.1 × 10−4)	0.455
Tracking	−0.294	1	0.440 (0.010)	0.154
Tapping	−0.041	0.926	< 0.20 (> 0.1)	0.206
Baseline speed	−0.125	0.880	< 0.20 (> 0.1)	0.204
Motor timing	−0.320	0.867	0.701 (3 × 10−6)	0.256
Combined score	0.0	1	0.344 (0.027)	0.605

^aMean and variance based on control sample consisting of sibling pairs described elsewhere.^5–9

^bHeritability models were adjusted by age, sex, and parent- and teacher-based Conners' questionnaires.

^cProportion of variance due to all final covariates according to SOLAR models.