Table 2.
Effect Sizes (r) and Ns for Family/Adoption Studies Included in the Meta-Analysis
| Study (Author, Year) | Operationalization/Measure | Assessment Method | Age Group | Sex | P-O r (N) | Bio-Sibs r (N) | Adoptive-Sibs r (N) | M-O (Adoptive) r (N) | Adoptive Relatives* |
|---|---|---|---|---|---|---|---|---|---|
| Dougherty et al. 2003 | Impulsivity | BIS | Children/Adolescents | M+F | −.38 (28) | -- | -- | -- | -- |
|
| |||||||||
| Loehlin et al. 1976 | Impulsivity | TTS | Adults | M+F | .10 (117) | .07 (102) | −.02 (143) | .04 (541) | -- |
| M+F | .09 (149) | ||||||||
|
| |||||||||
| Plomin et al. 1991 | Impulsivity | EASI | Children | M+F | −.01(235) | -- | .03 (65) | -- | −.02 (222) |
| .09 (222) | |||||||||
| .12 (77) | |||||||||
Note.
*
= adoptive relatives including adoptive mother – biological child, or adopted child –adoptive mother, or adoptive siblings; P-O= parent offspring pairs; A-B= adopted child biological parent; A-A= adopted child adoptive mother; adoptive sibs= adoptive siblings; bio sibs= biological siblings; M-O= adoptive mother – offspring; r = Pearson or Intraclass twin correlations; N = number of participants (family pairs); BIS= Barratt Impulsiveness Scale; BIS= Behavioral Inhibition System; EASI=extraversion, agreeableness, sociability, impulsivity; TTS= Thurstone Temperament Schedule