DeFries–Fulker regression
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In
Approach
DeFries–Fulker regression analysis is based on the differences in the magnitude of
Modifications
Since the DF regression approach was first proposed in 1985, other researchers have proposed modified versions of the DF model that take additional factors into account, including observed covariates[6] and opposite-sex DZ twins.[7]
Regression analysis
The probands are chosen with scores that fall below a "cutoff" for what is considered "extreme", and regression is then used to predict the co-twin scores based on those of the probands and a term reflecting whether the twin pair is MZ (1.0) or DZ (0.5).[8] The formula used for DF regression is:
- C = B1P + B2R + K
where C = expected co-twin score, P = proband score, R = coefficient of relationship (0.5 for DZ twins, 1.0 for MZ twins), and K = regression constant. B1 represents a measure of co-twin relatedness separate from that of zygosity, while B2 can be converted into an estimate of the heritability of extreme scores on the trait.[5] By comparing MZ and DZ co-twins in this manner, an estimate of "group heritability" is generated.[3]
References
- ISBN 978-0470860809.
- S2CID 1172312.
- ^ PMID 26817721.
- S2CID 37412119.
- ^ a b "DeFries-Fulker multiple regression analysis". Erik Willcutt website. University of Colorado Boulder. Retrieved 2018-06-20.
- PMID 23264207.
- S2CID 42718780.
- S2CID 37088113.