Few would dispute the truth of the statement People are Different', but there is much controversy over *why.* This book authoritatively explains the methods used to understand human variation, and extends them far beyond the primary nature or nurture' question. After chapters on basic statistics, biometrical genetics, matrix algebra and path analysis, there is a state-of-the-art account of how to fit genetic models using the LISREL package.
The authors explain not only the assumptions of the twin method, but how to test them. The elementary model is expanded to cover sex limitation, sibling interaction, multivariate and longitudinal data, observer ratings, and twin-family studies. Throughout, the methods are illustrated by applications to diverse areas such as obesity, major depression, alcohol comsumption, delinquency, allergies, and common fears.

Zusammenfassung
Based on NATO NFWO and NIMH Funded Workshops taught in Leuven, Belgium (1987, 1989, and 1991) and Boulder, Colorado, U.S.A. (1990).

Inhalt
1 The Scope of Genetic Analyses.- 2 Data Summary.- 3 Biometrical Genetics.- 4 Matrix Algebra.- 5 Path Analysis and Structural Equations.- 6 LISREL Models and Methods.- 7 Model Fitting Functions and Optimization.- 8 Univariate Analysis.- 9 Power and Sample Size.- 10 Social Interaction.- 11 Sex-limitation and G × E Interaction.- 12 Multivariate Analysis.- 13 Direction of Causation.- 14 Repeated Measures.- 15 Longitudinal Mean Trends.- 16 Observer Ratings.- 17 Assortment and Cultural Transmission.- 18 Future Directions.- Appendices.- A List of Participants.- B The Greek Alphabet.- C LISREL Scripts for Univariate Models.- C.1 Path Coefficients Model.- C.2 Variance Components Model.- C.3 Model for Means and Covariances.- C.4 Univariate Genetic Model for Twin pairs and Singles.- C.5 Age-correction Model.- D LISREL Script for Power Calculation.- D.1 ACE Model for Power Calculations.- E LISREL Scripts for Multivariate Models.- E.1 Genetic Factor Model.- E.2 Genetic Factor Model Using z Variables.- E.3 Bivariate Genetic Factor Model.- E.4 Genetic Cholesky Model.- E.5 Independent Pathway Model.- E.6 Common Pathway Model.- F LISREL Script for Sibling Interaction Model.- F.1 Sibling Interaction Model.- G LISREL Scripts for Sex and G × E Interaction.- G.1 General Model for Scalar Sex-Limitation.- G.2 Scalar Sex-Limitation Model.- G.3 General Model for G × E Interaction.- G.4 Scalar G × E interaction model.- H LISREL Script for Rater Bias Model.- H.1 Rater Bias Model.- H.2 CBC Items for Internalizing Scale Score.- I LISREL Scripts for Direction of Causation.- I.1 Reciprocal Causation Model.- I.2 Bivariate Genetic Model.- I.3 Bivariate Genetic Cholesky Model.- J LISREL Script and Data for Simplex Model.- J.1 Data Matrix for Phenotypic Simplex Model.- J.2 Genetic Simplex Model.-J.3 Data Matrices for Genetic Simplex Model.- J.4 Output from Genetic Simplex Model.- J.5 Output from Genetic Factor Model.- K LISREL Scripts for Assortment Models.- K.1 Social Homogamy Model.- K.2 Phenotypic Assortment Model.