One other element of The Happiness Advantage that rubs me the wrong way is playing loosely with causality and correlation. Achor notes that there is a difference, but then goes on to describe a particular experiment which he asserts as showing causality. The experiment is actually pretty elegant. Researchers coded journals that a group of nuns kept decades ago for signs of happiness, then correlated those levels of happiness against how long the nuns lived. And, indeed, happier nuns lived a lot longer.
That’s awesome, and certainly provides support for his position that happiness is a precursor to success (or in this case, health), not a result of it.
But to assert that causality in this experiment is clear is disingenuous. It’s just add possible that the longer lived nuns were healthier from the beginning, which made them happier in youth. Or maybe there is some other third factor that correlates with both happiness and health.
Just because a study is imperfect doesn’t make it imuseful, but an author invoking research to stake a position has a responsibility to deal with the limitations of that research.