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Crawford, Charles B.; DeFries, J. C. – Multivariate Behavioral Research, 1978
The application of component analysis to phenotypic, genetic, and environmental correlation matrices is discussed. Formulas for computation of component scores and the interpretation of factors is discussed. An example is presented. (Author/JKS)
Descriptors: Correlation, Environmental Research, Factor Analysis, Genetics
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Plomin, Robert; DeFries, J. C. – Child Development, 1983
Provides an overview of a longitudinal, prospective, multivariate adoption study of behavioral development and discusses the results of analyses of cognitive measures and environmental assessments as examples of the types of information that can emerge from a design of this sort. (Author/RH)
Descriptors: Adoption, Behavior Development, Biological Influences, Children
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Plomin, Robert; DeFries, J. C. – Intelligence, 1985
The present study is a behavioral genetic analysis of specific cognitive abilities in early childhood. Parent-offspring data for adopted children and nonadopted children in the Colorado Adoption Project were used. Significant correlations were found between biological mothers' IQ and the IQ of offspring, but not for specific cognitive abilities.…
Descriptors: Adopted Children, Analysis of Variance, Biological Parents, Cognitive Ability
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DeFries, J. C.; And Others – Intelligence, 1981
Results from the Colorado Adoption Project, a longitudinal study initiated in 1975, are reported. The cognitive ability of parents and measures of one-year olds' mental development were significantly correlated for all three parent/child comparisons. Caldwell's HOME Responsibility measure was correlated with infant intelligence in adoptive and…
Descriptors: Adopted Children, Adults, Cognitive Measurement, Correlation
Peer reviewed Peer reviewed
Plomin, Robert; DeFries, J. C. – Intelligence, 1980
Extensive data on twins, nontwin siblings, siblings separated by adoption, and parent-child similarity indicate that the heritability of intelligence is closer to .50 than to .70. Differences could be due to environmental or genetic changes in the population, or to methodology. (Author/CP)
Descriptors: Adopted Children, Correlation, Environmental Influences, Family Influence