In mid-December, The Economist ran
an article debunking the notion that life is "a long slow decline from
sunlit uplands towards the valley of death." Instead, people should think
of life's journey as a "U-bend," the magazine argued:
When people start out on adult life, they are, on average, pretty cheerful. Things go downhill from youth to middle age until they reach a nadir commonly known as the mid-life crisis ... The surprising part happens after that. Although as people move towards old age they lose things they treasure--vitality, mental sharpness and looks--they also gain what people spend their lives pursuing: happiness.
But is that true? The magazine cited a number of studies and highlighted one graph from a paper
by researchers at Stony Brook and Princeton.
Intrigued, Andrew Gelman, a statistics professor at Columbia University, resolved
to find the U for himself. He downloaded data from the General Social
Survey and graphed average happiness level as a function of age. But,
despite considerable tinkering with the data, a U never materialized in
his graphs. Gelman concludes:
My goal is not to debunk but to push toward some broader thinking. People are always trying to explain what's behind a stylized fact, which is fine, but sometimes they're explaining things that aren't really happening, just like those theoretical physicists who, shortly after the Fleischmann-Pons experiment, came up with ingenious models of cold fusion. These theorists were brilliant but they were doomed because they were modeling a phenomenon which (most likely) doesn't exist.
A comment from a few days ago by Eric Rasmusen seems relevant, connecting this to general issues of confirmation bias. If you make enough graphs and you're looking for a U, you'll find it. I'm not denying the U is there, I'm just questioning the centrality of the U to the larger story of age, happiness, and life satisfaction. There appear to be many different age patterns and it's not clear to me that the U should be considered the paradigm.
(h/t: Tyler Cowen)