Happiness is one of the most important aspects of our lives and it’s influenced by several factors. It is useful to observe and analyze data from the World Happiness Report to get an idea of the happiest countries, a publication of the ONU's non-profit organization “Sustainable Development Solutions Network”, produced annually since 2012.

The WHR uses data taken from the Gallup World Poll, an American data analysis and consulting firm, which conducts a survey using the Cantril scale, by having the respondents score themselves from 0 to 10 according to their preferences.

The sample size used to draw up the World Happiness Report is about 3,000 people from each country, who answered to the Gallup World Poll, with a 95% confidence interval.

In 2019 report there were 155 countries, while in 2022 the number was reduced to 146 and, also due to Covid, some data weren’t found by WHR due to lack of information about some country variables or inability to find them, so these unknown values were considered as 0.

The variables covered by this analysis are: 'GDP_PC' (GDP per capita), 'SOC_SUP' (social support), 'HLE' (life expectancy at birth), 'FTMLC' (freedom to make life choices), 'GEN' (generosity), and 'POC' (perception of corruption); these six factors make up the 'Score', i.e., the rating awarded each year for the ranking of the countries with the greatest happiness.

Below are the WHR 2019 and WHR 2022 rankings, the last one considers data from 2018-2021, influenced by the Covid-19 pandemic.

For the fifth consecutive year, Finland is the happiest country in the world, with a score of 7,821, followed by Denmark (7,636), always in the best position, and Iceland (7,557).

It’s important to notice that the top positions are predominantly occupied by Northern European countries; Italy is in 31st place, climbing five positions compared to 2019, thus showing a fair increase in our country's happiness index.

The two rankings show that individuals' happiness ratings have remained unchanged and have not worsened as a result of Covid.

Regarding to the WHR2022 results, through univariate analysis and in particular, with the representation of the main values by means of boxplots, we observed that the average score of all countries in the WHR is 5.554, while the top score is 7.821.

Indeed, the average score before the pandemic (WHR 2019) was slightly lower (5.413), and the Northern European countries always remain in the top positions, denoting certainly a growth of these countries in recent decades, that has led to an excellent quality of life.

With reference to the measures of variability, in both reports, Score is the variable with the highest variance and generosity with the lowest; starting from the pre-covid period up to this year, there is a decrease in the variances of all variables, except for freedom to make life choices and perception of corruption, for which they increase slightly.

The bivariate analysis produced essentially the same results in the two reports: it allowed us to observe a strong positive correlation between GDP per capita and life expectancy at birth (0.8153860 in 2022 and 0.8328336 in 2019), a phenomenon that represents perfectly the reality; moreover, generosity, which is weakly correlated with the score, unlike the other variables, has a smaller impact on each country's final score.

The score was clearly the variable with the highest correlation with the other variables, with almost identical values for the two years.

The multiple linear regression model that we used was:

*Score=β0 + β1GDP_PC + β2SOC_SUPP + β3HLE + β4FTMLC + β5GEN + β6POC + ε*

The coefficient of determination R2 was 0.7787 in 2019 and 0.7737 in 2022, expressing the great goodness of the model in both reports; the model overall was significant at each level since we obtained a very low and identical p-value in the two years (2.2e-16), and with a very high critical value of the F-statistic, with a slight superiority in 2019.

The variables emerged significant at lower levels of significance in 2019 than in 2022, since in the former case GDP per capita was also significant at level 0.1%, while thereafter only at level 1%.

As far as the other variables are concerned, they were all significant at least at the 10% level of significance, except for generosity, which, in 2019, with a very high p-value (0.333507), wasn’t significant at any level, while in 2022 it was significant at the 10% level.

The analysis of the residuals, in both cases, showed that they are well distributed above and below the mean, and there’s no trend in the distribution of them; furthermore, through the normal probability plot of the residuals, we can observe how normality is respected by the model.

The cluster analysis carried out with Ward's method (hierarchical method) was very important in order to take into account the exact number of clusters, i.e. 2, for both reports; in fact, the dendrograms obtained turned out to be very similar, and the same for the elbow method graphic; on the other hand, differences were revealed with reference to the matrix of the two clusters after the dendrogram was cut: infact, in 2019, a worse separation between the two clusters is evident than in 2022.

The cluster analysis using the k-means method produced 2 clusters too, with the number of individuals in each cluster slightly different from 2019 to 2022; the within-cluster variability (SSW) is quite high, however, decreasing from 62.8% in 2019 to 62.3% in 2022.

Thus, the happiness of countries depends on a myriad of factors, some of them were analyzed in the reports; however, there are variables not considered by the WHR, but which absolutely affect the state of mind of all individuals every day, namely interpersonal dynamics and social relationships with other people, which are very difficult to quantify and examine through statistical analysis techniques; therefore, this is a limitation of this study, which can be resolved, for example, through in-depth research and through factor analysis, in order to find latent variables, starting from observable and measurable variables.

In conclusion, very similar results were achieved about the World Happiness Report of 2019 and 2022; there was therefore a very slight influence of the Covid-19, which shocked our lives profoundly, but which didn’t impact excessively the WHR, which, despite being a benchmark for understanding the well-being situation for each country, doesn’t consider all the dynamics and variables of life.

## Comentarios