Happiness is a basic human emotion, but people often make assumptions about happiness that empirical research does not support. For example, people often assume that most people feel unhappy and dissatisfied with their lives, but research shows this is not true. Most people describe themselves as fairly happy even if they are in less than ideal circumstances. Surprisingly, researchers have not found a consistent positive correlation between happiness and factors such as wealth, age, intelligence, physical attractiveness, or parenthood—factors that many people commonly associate with happiness.

Although circumstances do not reliably predict happiness, some circumstances do correlate with increased happiness. These include having a good social network, being married, having a satisfying job, and having strong religious convictions. These circumstances, however, are only correlated with happiness. As explained on page 10, correlation does not necessarily mean causation. Research also shows that happiness tends to depend on people’s expectations of life and on how people compare themselves to their peers.