Correlational finding on Happiness and subject: What one eats

StudyMujcic & Oswald (2016): study AU 2007
TitleEvolution of Well-Being and Happiness After Increases in Consumption of Fruit and Vegetables.
SourceAmerican Journal of Public Health, 2016, Vol 106, 1504 - 1510
URLhttps://www.ncbi.nlm.nih.gov/pubmed/27400354
DOIdoi: 10.2105/AJPH.2016.303260.
Public18+ aged general public, Australia, followed 3 years 2007-2009
SampleProbability multi-stage cluster sample
Non-Response
Respondents N =12385

Correlate
Author's labelChange consumption fruits and vegetables
Page in Source table 1 + 2
Our classificationWhat one eats
Operationalization
Selfreported consumption of fruit and vegetables in 
portions per day in a typical week
1
2
3
4
5
6 or more
Observed distributionM: 3,84; SD: 2,01
Remarks
Change over 3 years: T1: 2007, T2: 2008, T3: 2009

Observed Relation with Happiness
Happiness
Measure
StatisticsElaboration/Remarks
O-SLW-u-sq-n-11-db-fix=+.03 p < .002
CHANGE happiness by CHANGE portions fruits and 
vegetables
CI95 [+0.01, +0.04] no controls

Meaning: Change from 1 to 6 servings an day would 
correspond with a gain of 0,24 on this 0-10 
happiness scale
Set Image size:   

O-SLW-u-sq-n-11-db-fix=+.03 p < .003
Controled for set A
O-SLW-u-sq-n-11-db-fix=+.02 p < .10
Additionally controled for set B
M-TH-cm-sq-v-6-ab-fix=+.02 p < .003
CI95 [+.001, - +003) no controls
M-TH-cm-sq-v-6-ab-fix=+.02 p < .02
Controled for set A
M-TH-cm-sq-v-6-ab-fix=+.02 p < .017
Additionally controled for set B

Control variables SET A
- socio-demographic characteristics
  - age
  - income
  - education
  - employmeent
- long-term health condition
- number of children under age 4

Control variables SET B
- drinking alcohol
- smoking
- eating behaviors
  - never eat red meat
  - never eat fish
  - drink low fat or skinny milk
  - avoid fat foods
- BMI
- regular exercise

Granger test suggests that causality runs from 
nutrition to happiness and not reversedly


Appendix 1: Happiness measures used
CodeFull Text
M-TH-cm-sq-v-6-aSelfreport on single question:

During the past 4 weeks….. Have you been a happy person?
6 all of the time
5 most of the time
4 a good bit of the time
3 some of the time
2 a little of the time
1 none of the time

Item MH5 in SF-36 (Medical Outcome Study 36 item Short Form)
O-SLW-u-sq-n-11-dSelfreport on single question:

All things considered, how satisfied are you with your life?
Again, pick a number between 0 and 10 to indicate how satisfied you are.
0 totally dissatisfied
1
2
3
4
5
6
7
8
9
10 totally satisfied


Appendix 2: Statistics used
SymbolExplanation
b-fixREGRESSION COEFICIENT in fixed effects analysis
Type: test statistic
WDH symbol: b-fix
Primary correlate level: metric
Secondary correlate level: nonmetric
Happiness level: metric
Theoretical range: unlimited
Meaning:
Variant of usual (non-standardized) regression coefficient (b), which controls for the secondary variables, by focusing on differences from a fixed level, such as the mean in a category. Aims to reduce the residual variance and to improve the precision of the regression coefficient.

References:
Wikipedia: http://en.wikipedia.org/wiki/Fixed_effects_model
Non-technical text: http://www.jblumenstock.com/files/courses/econ174/FEModels.pdf
Source:
Ruut Veenhoven, World Database of Happiness, Collection of Correlational Findings, Erasmus University Rotterdam.
https://worlddatabaseofhappiness.eur.nl