Hp. Kohler et Jl. Rodgers, DF-Analyses of heritability with double-entry twin data: Asymptotic standard errors and efficient estimation, BEHAV GENET, 31(2), 2001, pp. 179-191
In this paper we establish the asymptotic distribution of DeFries Fulker (1
985) regression estimates for heritability and shared environmental influen
ces with double-entry twin data. A simple formula to estimate the covarianc
e matrix of the coefficients in DF-regressions is provided, and application
s to simulated data and Danish twin data show that this method can substant
ially increase the statistical power of the analyses. We also provide an 'e
fficient DF-analysis' that yields more precise estimates when additional co
variates are included among the explanatory variables.