| Correlate as named by investigator | People investigated | |
| Finding | Positive/negative valence of words used in books in nations | 18+ aged, general public, 6 EU nations, 1973-2000 |
| Finding | Importance of happiness | Adults, general public, 30 countries, 1974-1999 |
| Finding | Fear of happiness | Students, 14 nations, 2014 |