Table 2.

Twin Correlations for Binge Eating by Estradiol Levels.

Estrogen Groups	MZ Pairs	DZ Pairs	Z Test of Independence	p	q
Full Sample (N =267 pairs (534 twins))
Lower Estradiol (MZ n = 67 pairs; DZ n = 62 pairs)	.70*** (.55, .80)	.10 (.15, .34)	4.25	<.001	.77
Higher Estradiol (MZ n = 69 pairs; DZ n = 69 pairs)	.11 (-.13, .34)	.27* (.04, .48)	0.96	.34	.16
Pre-Menarcheal Twins Only (N = 141 pairs (282 twins))
Lower Estradiol (MZ n = 39 pairs; DZ n = 31 pairs)	.74*** (.55, .86)	.50** (.18, .73)	1.59	.11	.40
Higher Estradiol (MZ n = 36 pairs; DZ n = 35 pairs)	.001 (-.33, .33)	.22 (-.12, .52)	0.90	.37	.22

Note. MZ = monozygotic; DZ = dizygotic; Z Test of Independence = a z test of significant differences between the MZ and DZ twin correlations; q = effect size for the difference between the two twin correlations (no effect q < .10, small effect q = .10-.30, medium effect q = .30-.50, large effect q > .50. The 95% confidence intervals are presented in parentheses. Binge eating scores were log transformed prior to analysis.

^*p < .05,

^***p < .001. The twin correlation is significantly different from zero.