The Contagion of Happiness

In a 20-year study of almost 5,000 people it was found that happiness is more contagious than previously thought.

While there are many determinants of happiness, whether an individual is happy also depends on whether others in the individual’s social network are happy. Happy people tend to be located in the centre of their local social networks and in large clusters of other happy people. The happiness of an individual is associated with the happiness of people up to three degrees removed in the social network. Happiness, in other words, is not merely a function of individual experience or individual choice but is also a property of groups of people. Indeed, changes in individual happiness can ripple through social networks and generate large scale structure in the network, giving rise to clusters of happy and unhappy individuals. These results are even more remarkable considering that happiness requires close physical proximity to spread and that the effect decays over time.

The New York Times covers the findings, producing two typically elegant graphics to display some of the fascinating results (for example, it was found that a neighbour’s mood effects your happiness drastically more than a cohabiting spouse’s).

The authors of the study—who evidently specialise in social network analysis—have previously found that both obesity and quitting smoking are socially contagious; but should we really be inferring these “network effect” conclusions?

Another article, printed in the same issue of the British Medical Journal, uses the same research design to show how it can lead to conclusions that disappear once environmental confounders are controlled—in this case finding that height, headaches, and acne are contagious, when this conclusion is evidently a confusion between correlation and causation.

via Mind Hacks