The economy may have boomed in China, but happiness hasn't boomed along with it, according to a University of Southern California study released Monday. Happiness levels dropped and then bounced back over the last two decades, changing little on the whole even as Chinese incomes grew at least fourfold.

The swings in the level of happiness seem to be tied to unemployment, said economics professor Richard A. Easterlin, a pioneering scholar in the happiness field and one of the authors of the report published in the Proceedings of the National Academy of Sciences. Other factors that have dragged down happiness levels are increased inequality and the disappearance of the social safety net.

“When unemployment is up, not only do the unemployed become less happy, but the employed feel greater insecurity,” Easterlin said. “The clear lesson from China is how important it is for people’s happiness to have jobs and a fair amount of certainty about those jobs, as well as a social safety net.”

Happiness is under the microscope in China, which economists have eyed as a real-life laboratory to study how money, inequality and change are tied to our satisfaction with life. The Chinese government has even gotten in on the act, with cities devising new indexes to measure happiness and politicians pontificating on the importance of xingfu, The Times’ Barbara Demick reported last year.