The term “quality of life” is widely used by psychologists, sociologists, economists, policy makers, and others. However, what is meant by quality of life varies greatly depending on the context. In some settings, it may include such components as employment status, income, housing, material possessions, environment, working conditions, or the availability of public services. The kinds of indices that reflect quality of life from a medical or health viewpoint are very different, and would include those aspects that might be influenced not only by conditions or diseases but also by medical treatment or other types of interventions. Thus, the term “health-related quality of life (HRQL)” is now commonly used to mean the measurement of one’s life quality from a health or medical perspective.