Measurement and Analysis of Quality of Life in Epidemiology

Health related Quality of Life (HrQoL) is one of the most important outcome measure in clinical trials over the past 20 years. More recently, it became also more important in epidemiological surveys, where unlike clinical trials, the number of end points involved is generally larger. In both setting, Epidemiology, or clinical trials, its measurement and statistical analysis remain an issue. The validation of a Health related Quality of Life (HrQoL) measurement is generally mainly done by internal consistency methods as external standards or experts are generally not available. These methods are mainly based on the statistical validation, using goodness of fit tests, of measurement models. We will show in this chapter, how such validation, can be done using the empirical Backward Reliability Curve (the α -curve). Finally, we present some new simulation and real data results.