Comparing rates of happiness across countries can be tricky, given cultural, economic and social differences that testing may not capture. However, while some “outliers” defy the idea that wealthier nations are happier – Nigeria is very happy; Japan, not so much – other factors, such as age, marriage and jobs, regularly show up in happiness calculations. Age has a “U-shaped relationship” with contentment; people are least happy in their mid- to late 40s. Being married makes people happier, being unemployed makes them unhappy and being healthy makes them very happy. Education, gender and type of job have varying effects on joyfulness, depending on levels of educational opportunity, gender bias and insecurities about self-employment. For instance, self-employed people are more satisfied in the U.S. and in Russia, where that’s a routine option, than in Latin America, where the lack of jobs forces people to work for themselves. In America, women are happier. In Russia, men are happier. And, in Latin America, men and women are equally happy. Among these three regions, minorities are more content only in Russia because political changes after communism gave them greater status. Studies in Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan show similar determinants of happiness as in other nations, except in “social capital.” Central Asians do not associate trust, religion and community with happiness, most likely due to their experiences within the former Soviet Union and their evolving political situations. Surveying residents’ level of contentment in Turkmenistan was impossible “due to the complex political situation.”

Among the citizens of transitional nations, Cubans stands out because they reputedly are “remarkably cheerful,” though polling shows less joy than in other Latin American nations. Cubans in Havana and Santiago favourably cite their superior health care and educational prospects but rank their “economic opportunity” satisfaction lower than that of other Latin Americans.

While optimism is related to happiness in most regions, in Africa it is “inversely correlated” to poverty: Poorer people are more optimistic about the next generation’s future. This may be because only the eternally hopeful can endure Africa’s vast, endemic poverty, or because people have made a “realistic assessment that conditions are so bad they can only improve.”