“Everywhere that I have studied happiness some very simple patterns hold: a stable marriage, good health, and enough (but not too much) income are good for happiness. Unemployment, divorce, and economic instability are terrible for happiness—everywhere that happiness is studied.”

Diener believes he can measure happiness. He conducted a study that found a correlation between the incomes of undergraduates nineteen years after graduation with their level of cheerfulness.8 His research also showed that happy people have higher supervisor ratings, higher organizational citizenship, and higher incomes.