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London: The average guy's happiness is based on a combo of personal wealth, possessions and optimism, according to a global survey.

A country's gross domestic product per capita did not have as much of an impact on the average person's happiness, according to the research based on responses of 806,526 people in 135 countries from 2005 to 2011.

Happiness expert and psychologist Edward Diener from the University of Illinois, who led the study, said: "We've found that rising income does lead to rising happiness, but it depends on people being optimistic, not having sky-high desires, and the average person being actually able to afford more things."

Researchers gathered data from the first Gallup World Poll, which conducted surveys by phone and door-to-door visits, the Journal of Personality and Social Psychology reports.

Respondents rated their lives on a scale from zero (worst possible life) to 10 (best possible life) and answered questions about positive or negative emotions experienced the previous day, according to an Illinois statement.

The researchers looked at each country's gross domestic product per capita, obtained from the International Monetary Fund (IMF), and each respondent's household income.

The survey asked participants if they had enough money for food, whether they had enough money for shelter, if they owned a TV set and if their household had an internet connection. It also asked about their optimism for the future and their satisfaction with their current standard of living.

This new research helps bring clarification to the "Easterlin Paradox," a concept introduced in 1974 that suggested the economic growth of nations does not lead to more happiness, according to Diener.