Finland has been named the happiest country in the world for eight years in a row, according to the World Happiness Report, which is published annually by the United Nations Sustainable Development Solutions Network.

But here’s the interesting part, when we talk about “happiness” in this context, it’s not just about good vibes or smiling selfies. The rankings are based on something much deeper — the science of subjective well-being, pulled from Gallup’s World Poll, which surveys people in over 150 countries.

So how does it actually work?

Gallup asks people a series of life evaluation questions. One of the most important is called the Cantril Ladder question:

“Imagine a ladder with steps numbered from 0 at the bottom to 10  ...