Correlational finding on Happiness and Twin or triplet child
Subject code: F01ac04

StudyLoehlin & Nichols (1976): study US 1963
TitleHeredity, Environment and Personality. A Study of 850 Sets of Twins.
SourceUniversity of Texas Press, 1976, Austin, USA
PublicAdolescent same-sex twins, USA, 1963
SampleProbability stratified sample
Non-Response29 %
Respondents N =850

Correlate
Author's labelBeing an identical or fraternal twins
Page in Source 14
Our classificationTwin or triplet child, code F01ac04
Operationalization
A Identical twins
  a male
  b female 
B Fraternal twins
  a male
  b female
Observed distributionN for happiness means = A: 486, Aa: 204, Ab: 282, B: 320, Ba: 130, Bb: 190 N for % cheerful & satisfied = A: 509, Aa: 216, Ab: 293, B: 330, Ba: 135, Bb: 195
Remarks
All twins are same sex.

Observed Relation with Happiness
Happiness
Measure
StatisticsElaboration/Remarks
O-HP-g-sq-v-7-aDM= ns
                male      female     all
Identical twin  M = 6,11  M = 6,28   M = 6,21
Fraternal twin  M = 6,03  M = 6,12   M = 6,08
O-HP-g-sq-v-2-bD%= ns
% cheerful           male      female     all
Identical twin       65%        77%       72%
Fraternal twin       69%        76%       73%
O-HP-g-sq-v-2-cD%= ns
% satisfied          male      female     all
Identical twin       83%        77%       80%
Fraternal twin       75%        81%       79%

Significance tests computed by us, assuming that 
these samples are a probability sample of a wider 
population of twins.


Appendix 1: Happiness measures used
CodeFull Text
O-HP-g-sq-v-2-bSelfreport on single question:

Which of the following adjectives do you consider to be descriptive of yourself? Circle the number besides any adjective that you might use in describing yourself to someone else. Your behavior will vary with situation of course, so circle the numbers besides adjectives that apply to you frequently, even though they may not apply all the time. Work rapidly putting down your first thoughts.

Cheerful
1 no (not circled)
2 yes (circled)

Item in longer personality inventory
O-HP-g-sq-v-2-cSelfreport on single question:

Which of the following adjectives do you consider to be descriptive of yourself? Circle the number besides any adjective that you might use in describing yourself to someone else. Your behavior will vary with situation of course, so circle the numbers besides adjectives that apply to you frequently, even though they may not apply all the time. Work rapidly putting down your first thoughts.

Satisfied
1 no (not circled)
2 yes (circled)

Item in longer personality inventory
O-HP-g-sq-v-7-aSelfreport on single question:

Below are a number of dimensions on which people can vary. Please rate yourself on each dimension as honestly as you can. Many of the traits depend on the situation of course, but try to rate yourself as you usually are.

Happy-unhappy
7 very happy
6 fairly happy
5 slightly happy
4 neither or both
3 slightly unhappy
2 fairly unhappy
1 very unhappy

Item in longer personality inventory
Numbers reversed original presentation (happy 1, unhappy 7)


Appendix 2: Statistics used
SymbolExplanation
D%DIFFERENCE in PERCENTAGES
Type: descriptive statistic only.
Measurement level: Correlate level: dichotomous, but nominal or ordinal theoretically possible as well. Happiness level: dichotomous
Range: [-100; +100]

Meaning: the difference of the percentages happy people at two correlate levels.
DMDIFFERENCE of MEANS
Type: descriptive statistic only.
Measurement level: Correlate: dichotomous, Happiness: metric
Range: depending on the happiness rating scale of the author; range symmetric about zero.

Meaning: the difference of the mean happiness, as measured on the author's rating scale, between the two correlate levels.
Source:
Ruut Veenhoven, World Database of Happiness, Collection of Correlational Findings, Erasmus University Rotterdam.
https://worlddatabaseofhappiness.eur.nl