Researchers then broke down the happiness effect on the basis of a participant's relationship to others and their proximity to each other.

What did they find? Here's the ranking, from greatest impact on happiness to least:

1. Nearby mutual friends (who literally ranked off the charts; the probability of increasing happiness is 148 percent)
2. Next-door neighbor
3. Nearby friend (a person whom the participant named as a friend but the "friend" did not reciprocate that label)
4. Nearby friend-perceived friend (a person whom the participant did not name as a friend but who claimed to be a friend of the participant)
5. Nearby sibling
6. Co-resident spouse
7. Distant sibling
8. Non-co-resident spouse
9. Same-block neighbor
10. Distant friend