The first data set used here is from large-scale epidemiological surveys implemented as part of the World Health Organization World Mental Health Survey Initiative (WMHSI). These surveys were conducted between 2002 and 2005 in 10 OECD countries. They use a common diagnostic instrument to measure the occurrence of various types of disorders, their nature and intensity, and the treatment provided. Disorders considered include anxiety disorders, mood disorders, disorders linked to impulse control and disorders due to use of alcohol and drugs. All disorders are classified as serious, moderate, or mild.
The second set of data is from the European Quality of Life Survey conducted in 2007 by the European Foundation for the Improvement of Living and Working Conditions. These data are based on the following question: Please indicate for each for the five statements which is closest to how you have been feeling over the last two weeks - I have felt cheerful and in good spirits; I have felt calm and relaxed; I have felt active and vigorous; I woke up feeling fresh and rested; my day has been filled with things that interest me (all of the time, most of the time, more than half of the time, less than half of the time, some of the time, never). The total score on all statements is multiplied by 4 to get a score that has a maximum value of 100.