Table 7. Summary of best fitting model (as indicated by AIC) for three indices of SES.

§ Best fitting model	SES index 1								SES index 2					SES index 3
	2	3	4	7	9	10	12	14	7	9	10	12	14	9	10	12	14
ace βA βC βE βM
βA = 0	◯
βC = 0
βE = 0			◯
βA = βC = 0
βA = βE = 0								⊙		⊙	⊙	⊙		⊙	⊙	⊙	⊙
βC = βE = 0						•
βA = βC = βE = 0		•		•			•		•				•

^§Best fitting model as indicated by Akaike's information criterion (AIC); SES index 1 = a composite of parental education and occupation acquired when the TEDS twins were 18 months old; SES index 2 = a composite of parental education and occupation acquired when the TEDS twins were 7 years old; SES index 3 = family income measured when the TEDS twins were 9 years old; a, c, e = unmoderated genetic, shared, and nonshared environmental path coefficients; β_A, β_C, β_E = moderated genetic, shared, and nonshared environmental path coefficients; β_M = main effect of moderator on mean of IQ; ◯ = includes C moderation; ⊙ = C moderation only.