title: DF-analyses of heritability with double-entry twin data: asymptotic standard errors and efficient estimation.
abstract: In this paper we establish the asymptotic distribution of DeFries Fulker (1985) regression estimates for heritability and shared environmental influences with double-entry twin data. A simple formula to estimate the covariance matrix of the coefficients in DF-regressions is provided, and applications to simulated data and Danish twin data show that this method can substantially increase the statistical power of the analyses. We also provide an 'efficient DF-analysis' that yields more precise estimates when additional covariates are included among the explanatory variables.
authors.affiliation: Head of Research Group on Social Dynamics and Fertility, Max Planck Institute for Demographic Research, Rostock, Germany. kohler@demogr.mpg.de
authors.forename: H P
authors.initials: HP
authors.lastname: Kohler
authors.forename: J L
authors.initials: JL
authors.lastname: Rodgers
mesh_terms: D000328:Adult; D001827:Body Height / Q000235:genetics; D015992:Body Mass Index; D003625:Data Collection / Q000706:statistics & numerical data; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008957:Models, Genetic; D010641:Phenotype; D012044:Regression Analysis; D012931:Social Environment; D018433:Twin Studies as Topic / Q000706:statistics & numerical data*; D014427:Twins / Q000235:genetics*