The authors of these chapters are the world's top experts on assessing Quality of Life. For example, the author of the first chapter is Sten Johansson, former Director of Statistics Sweden, responsible for creating the first comprehensive QOL assessment systems in the world, beginning in the 1960's. The author of the second chapter is Professor Ruut Veenhoven, known as the premier researcher on national happiness, having developed the largest database in the world on the subjective measures of well-being. Heinz-Herbert Noll is responsible for developing the unified Quality of Life measurement system for the new European Union, where up to 25 countries will be assessed using the same methodology and questionnaires.