Here are some reasons:
- The authors use satisfaction and happiness interchangeably. They are not the same construct and it will confuse those not familiar with the existing literature.
- The sample is taken from a few mailing lists of European economists.
- The study measures life satisfaction with a single question.
- The life satisfaction question is part of a broader survey focused on scientific misbehavior, which means that such information is going to be primed before the life satisfaction question.
- Meditation: Imagine that you conduct two studies: one in which you ask participants to reflect on all the good things that have happened to them in the past three months, followed by a life satisfaction question, and one in which you just ask them about life satisfaction. Is there a difference?
- I remain unconvinced that numeric ratings of life satisfaction can be meaningfully compared across populations. The French rate themselves as less healthy than Americans, but live an average of 3 years longer.
Still not convinced? The Maasai are a semi-nomadic African people in Kenya and the average Maasai is as satisfied as the economists in this study.