Each chapter of this book takes the effects of one of the six factors and begins with statistical evidence from Britain. It then goes on to compare data on individuals drawn from three panel studies for Germany, and Australia, the United States.
The approach, shortly resumed, consists in asking how much extra life-satisfaction can one additional unit of (income) for example bring.
What I did then was categorize all of the given most of the given research sources into this six categories, to give you an overview and to show you how complex actually life satisfaction can be. I will elaborate on three examples:
On income, Clark claims that the gain in happiness from an extra dollar of income varies greatly with income. In fact the gain in happiness is inversely proportional to income. So when a poor person gets a dollar from someone who is ten times richer than him or her, the poor person gains ten times more happiness than the rich person loses. There are studies that show that wellbeing rises with income until or even above 75.000 $, whereas others claim that income is a poor gauge for wellbeing.
Regarding work, it is paradoxical to see that people are unhappy working, but they feel even more unsatisfied when unemployed as the income is missing and the feeling of contributing is absent.
And regarding family, studies have been conducted to show that marriage can actually make you unhappier and lonelier that you would be if you were single. Of course there are also studies that claim the opposite.