Table 1.

Mean trait values by gene–environment stratum.

	exposure
genotype	0	1
0	${\overline{Y}}_{00}$ (s.d.00)	${\overline{Y}}_{01}$ (s.d.01)
1	${\overline{Y}}_{10}$ (s.d.10)	${\overline{Y}}_{11}$ (s.d.11)

Dichotomous exposure (1, exposed) and genotype coding (1, carrier of minor allele); Y¯ is mean trait in gene–environment stratum ij; s.d._ij is the standard deviation of the trait.