Correlational finding on Happiness and Happiness of sibblings
Subject code: H08ac04

StudyEmde et al. (1992): study US Colorado 1986
TitleTemperament, Emotion, and Cognition at Fourteen Months: The MacArthur Longitudinal Twin Study
SourceChild Development, Vol. 63, No. 6 (Dec., 1992), pp.1437-1455
URLhttp://www.jstor.org/stable/1131567
Public14 months aged, same-sex twin pairs, Colorado, United States, 1986-1989
SampleNon-probability purposive sample
Non-Response
Respondents N =398

Correlate
Author's labelHappiness of Twin siblings
Page in Source 1445, 1447, 1448
Our classificationHappiness of sibblings, code H08ac04
Operationalization
at 14 months, twin pairs were first observed at home 
and 2 weeks after that in the laboratory at the 
Institute for Behavioral Genetics in Boulder, behavior 
was videotaped and rated afterwards; parents completed 
questionnaire in the time between the home &  lab 
session;
Observed distributionN: 99 monozygotic twin pairs, 99 dizygotic twin pairs
Remarks
monozygotic (MZ) = identical
dizygotic (DZ) = non-identical

Heritability (h):
the extent to which observed variance in behavior can 
be attributed to genetic influence:
-> doubling the difference between the MZ and DZ 
correlations, because MZ twins are identical 
genetically, whereas the genetic correlation for DZ 
twins is assumed to be +.50

Shared Environment (c):
shared environmental influences (c), estimated in the 
twin method as twin resemblance not explained by 
heritability: twice the DZ correlation minus the MZ 
correlation (only detects major effects of shared 
environment)

for details of computations see DeFries & Fulker, 1985

Observed Relation with Happiness
Happiness
Measure
StatisticsElaboration/Remarks
A-CA-mi-tsb-v-7-ar=+.19 p < .01
Monozygotic Twins
A-CA-mi-tsb-v-7-ar=+.02 ns
Dizygotic Twins
A-CA-mi-tsb-v-7-a
Heritability component:       h=+.34 (ns)
Shared environment component: c=-.15 (ns)


Appendix 1: Happiness measures used
CodeFull Text
A-CA-mi-tsb-v-7-aTime sampling of prevalent mood during free play and Bayley test. Average of observations at 30 second intervals across 15 minutes of free play and 1 minute intervals for 4 alternate 5 minute segments of the Bayley test

Rated on 7 step scale, scale labels not reported


Appendix 2: Statistics used
SymbolExplanation
rPRODUCT-MOMENT CORRELATION COEFFICIENT (Also "Pearson's correlation coefficient' or simply 'correlation coefficient')
Type: test statistic.
Measurement level: Correlate: metric, Happiness: metric
Range: [-1; +1]

Meaning:
r = 0 no correlation ,
r = 1 perfect correlation, where high correlate values correspond with high happiness values, and
r = -1 perfect correlation, where high correlate values correspond with low happiness values.
Source:
Ruut Veenhoven, World Database of Happiness, Collection of Correlational Findings, Erasmus University Rotterdam.
https://worlddatabaseofhappiness.eur.nl