Group 25 Report – Measuring Joy: What Makes a Nation Happy?
Project Overview
We study why some countries report markedly higher life-satisfaction than others, using the World Happiness Report for 2019 (pre-COVID) and 2021 (mid-pandemic). Focusing on the six official explanatory components, we pose four research questions about economic resources, social cohesion, civil freedom, health, generosity, and regional clustering.
Dataset description (2019 and 2021 slices)
We analyse the 2019 sample (n = 156 countries) and the 2021 sample (n = 149) from the World Happiness Report.
The response variable is the Happiness Score – the national mean answer to Gallup’s Cantril Ladder (0 = worst possible life, 10 = best).
Six additive components
Factor |
Definition |
|---|---|
| GDP per capita | Ladder-point contribution from national income |
| Healthy life-expectancy | Contribution from expected healthy years |
| Social support | Contribution from having someone to rely on |
| Freedom | Contribution from feeling free to choose life course |
| Generosity | Contribution from recent charitable giving |
| Perceived corruption | Contribution reflecting cleaner institutions |
Country/region name and overall rank are descriptive only; all numeric analyses use the cleaned tibbles df2019 and df2021.
Research questions
RQ 1 – To what extent do GDP-per-capita and social support jointly predict 2019 Happiness Score?
RQ 2 – How strongly does perceived freedom to make life choices relate to 2019 Happiness Score?
RQ 3 – Do healthy life-expectancy and generosity together shape 2021 Happiness Score?
RQ 4 – Do countries from the same geographical region share similar happiness profiles?
Each question is addressed with at least two figures plus a formal statistical model.
Statistical evidence
| term | estimate | std.error | statistic | p.value | conf.low | conf.high |
|---|---|---|---|---|---|---|
| (Intercept) | 0.696 | 0.039 | 17.733 | 0 | 0.618 | 0.773 |
| gdp | 0.567 | 0.040 | 14.284 | 0 | 0.489 | 0.645 |
Each additional ladder-point of the GDP-per-capita contribution is associated with a 0.57 ± 0.08-point increase in the social-support contribution (R² ≈ 0.55, p < 10⁻²⁹).
Figure 2 – Coefficient plot
GDP β ≈ 1.35; Social-support β ≈ 1.54; Adjusted R² ≈ 0.77.
RQ 2 · Freedom to choose life course
Figure 3 – Contour density
The density ridge peaks at freedom ≈ 0.50 and happiness ≈ 6.0, confirming the upward trend.
Figure 4 – Linear fit
Statistical evidence
| term | estimate | std.error | statistic | p.value | conf.low | conf.high |
|---|---|---|---|---|---|---|
| (Intercept) | 3.679 | 0.215 | 17.075 | 0 | 3.253 | 4.104 |
| freedom_to_make_life_choices | 4.403 | 0.516 | 8.536 | 0 | 3.384 | 5.421 |
A full-scale freedom gain raises Happiness by 4.40 ± 0.52 points (R² ≈ 0.49, p < 2 × 10⁻¹⁶).
RQ 3 · Healthy life-expectancy × Generosity (2021)
Figure 5 – Hex-binned heat-map
Figure 6 – LOESS interaction
Statistical evidence
| term | estimate | std.error | statistic | p.value | conf.low | conf.high |
|---|---|---|---|---|---|---|
| (Intercept) | -2.570 | 0.546 | -4.710 | 0.000 | -3.649 | -1.492 |
| healthy_life_expectancy | 0.125 | 0.008 | 14.950 | 0.000 | 0.109 | 0.142 |
| generosity | -5.518 | 4.097 | -1.347 | 0.180 | -13.615 | 2.579 |
| healthy_life_expectancy:generosity | 0.098 | 0.064 | 1.544 | 0.125 | -0.028 | 0.224 |
Life-expectancy β ≈ 0.125 (p < 2 × 10⁻¹⁶); generosity & interaction ns; Adjusted R² ≈ 0.60.
RQ 4 · Regional similarity
Figure 7 – Dendrogram
Figure 8 – PCA scatter with 95 % ellipses
Statistical evidence
| term | df | sumsq | meansq | statistic | p.value |
|---|---|---|---|---|---|
| regional_indicator | 9 | 106.053 | 11.784 | 25.34 | 0 |
| Residuals | 139 | 64.637 | 0.465 | NA | NA |
One-way ANOVA: F(9, 139) ≈ 25.34, p < 2 × 10⁻¹⁶; regions explain ≈ 62% of cross-country happiness variance.
Silhouette width for the four-cluster solution is 0.46, indicating moderately distinct regional groupings.
Conclusions
Across both years, economic output, social support, and healthy life-span explain the bulk of cross-national happiness.
A two-variable model (GDP + support) accounts for 77 % of 2019 variance; perceived freedom adds a smaller but significant 4.40 ± 0.52 ladder-points per full-scale unit.
In 2021, healthy life-expectancy remains the strongest single correlate (≈ 0.13 points per extra healthy year), while generosity shows no reliable main or interaction effect.
Regional patterns are pronounced: an ANOVA indicates that ≈ 62 % of between-country variation sits at the regional level, with coherent clusters in Western Europe, Latin America, and Sub-Saharan Africa.
These findings suggest that policies promoting both economic security and social cohesion yield the largest well-being gains, and that civil freedom offers an additional but smaller boost.
Future work
Add control variables we already have.
Re-fit the 2019 multiple-regression model including healthy life-expectancy and generosity to see whether GDP and social support remain significant when the full set of components is considered.
Model-assumption checks.
Use residual-versus-fitted and QQ plots (via plot(lm_obj)) to confirm linearity and normal-error assumptions for each regression used in the report.
Compare pre- and mid-pandemic means.
Conduct paired t-tests (or Wilcoxon signed-rank tests if normality fails) on each component’s 2019 vs 2021 scores to quantify how the pandemic shifted the drivers.
Evaluate multicollinearity.
Compute variance-inflation factors (car::vif) for the full 2019 model; if VIF > 5, consider centred variables or principal-component regression (covered in lecture).
Visualise change over time.
Produce a simple line chart for the ten largest countries, plotting their Happiness Score in 2015, 2019, and 2021 to illustrate trajectories without advanced time-series methods.
Report uncertainty for cluster analysis.
Repeat the hierarchical clustering with single and average linkage and record whether regional groupings persist; discuss any instability instead of pursuing bootstrap or gap-stat techniques.