TABLE 4.

Simulation allowing heritability (h²) to vary by sex: average point estimates $({\overline{h}}_{Male}^2,{\overline{h}}_{Female}^2)$ across 1000 simulated datasets. In parentheses: true standard error (standard deviation of estimates across all datasets), average estimated standard error, and 95% confidence interval coverage rate. NACE-S and Falconer-S are the traditional NACE/Falconer methods except fit stratified by sex. "Npairs" is the number of twin pairs in each category: MZ male, MZ female, DZ male and DZ female.

Npairs	Model	${\overline{h}}_{Male}^2=0.60$	${\overline{h}}_{Female}^2=0.30$
450	NACE-S	0.60 (0.07, 0.07, 0.95)	0.30 (0.07, 0.07, 0.95)
	GEE2-NACE	0.60 (0.07, 0.07, 0.96)	0.30 (0.07, 0.07, 0.94)
	Falconer-S	0.60 (0.08, 0.06, 0.84)	0.30 (0.08, 0.06, 0.83)
	GEE2-Falconer	0.60 (0.08, 0.08, 0.96)	0.30 (0.08, 0.08, 0.95)
100	NACE-S	0.59 (0.14, 0.13, 0.90)	0.31 (0.15, 0.15, 0.96)
	GEE2NACE	0.59 (0.15, 0.14, 0.92)	0.31 (0.15, 0.14, 0.94)
	Falconer-S	0.60 (0.17, 0.12, 0.82)	0.31 (0.18, 0.12, 0.82)
	GEE2-Falconer	0.60 (0.17, 0.16, 0.92)	0.31 (0.17, 0.17, 0.95)