Table 1.

Twin pair agreement in rating presence or absence of biological parent alcohol problems for narrow versus broad ratings.

		TOTAL	Narrow Rating						Broad Rating
			Concordant Positive		Discordant				Concordant Positive		Discordant
		Na	N	%	N	%	ρ	S.E.	N	%	N	%	ρ	S.E.
Maternal Alcohol Problems
MZ Female Pairs -	EA	846–848	31	3.7	28	3.3	0.93#	0.03	44	5.2	37	4.8	0.92	0.02
	AA	111	5	4.5	7	6.3	0.86	0.10	9	8.1	10	9.0	0.85	0.08
DZ Female Pairs -	EA	656–657	18	2.7	35	5.3	0.81	0.06	33	5.0	39	5.9	0.87	0.04
	AA	141	6	4.3	15	10.6	0.68	0.14	11	7.8	17	12.1	0.76	0.10
Paternal Alcohol Problems
MZ Female Pairs -	EA	821–829	91	11.1	96	11.7	0.83	0.03	139	16.8	96	11.6	0.88	0.02
	AA	100–101	15	15.0	21	21.0	0.69	0.11	25	24.8	27	26.7	0.64*	0.11
DZ Female Pairs -	EA	636–642	72	11.3	80	12.6	0.82	0.04	113	17.6	78	12.2	0.88	0.02
	AA	130–131	22	17.0	21	16.2	0.80	0.07	30	22.9	24	18.3	0.80	0.07

ρ = tetrachoric correlation; SE = standard error;

^aNs for narrow-broad ratings;

^#MZ versus DZ agreement differs significantly by twin pair zygosity, in comparisons within ethnicity groups (EA: 0.93 vs. 0.81, p <. 05);

^*agreement differs significantly by ethnicity, in comparisons within zygosity groups (MZ: 0.88 vs. 0.64, p < .01).