"Wow," Oishi said in an email. "This is a very strong paper" in its approach.
Researchers drew on data from a huge sample of young Americans who were surveyed repeatedly. They were asked to rate their positive feelings such as happiness and hopefulness at age 16 and again at 18, and their satisfaction with life at 22. Researchers then compared their ratings with their income around age 29. The data came from nearly 15,000 participants at age 16, and at least 11,000 at the latter two ages.
Higher income at age 29 was consistently linked to greater happiness at the earlier ages. The least happy 16-year-olds, for example, went on to average about $10,000 a year less than the happiest. That disparity shrank by about half when the researchers statistically removed the effect of other influences such as ethnicity, health and education.
A happiness effect even appeared between siblings within their own families.
What's going on? Most likely, happiness raises productivity and helps a person work effectively with others, factors that promote success in the workplace, Oswald said. The study found that happier people were more likely to get a college degree and get hired and promoted.
Ed Diener, an authority on happiness research at the University of Illinois at Urbana-Champaign, said optimism probably plays a role because it helps people persist in their efforts and take on difficult goals. Since several studies, including his own, have now linked happiness to later income, that idea seems reliable, he said.
Parents should recognize that "the psychological well-being of their children is important in how well the kids will do in simple dollar terms later on," Oswald said. And unhappy people should realize that they might have to strive harder than others to focus on work and promotion rather than their unhappiness, he said.
Malcolm Ritter can be followed at http://www.twitter.com/malcolmritter
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