The equivalent of one completely well year of life, a measure designed to assess the benefits of health programs. The measure is used in a General Health Policy Model (GHPM). The well-year value is derived from measures of (1) life expectancy and (2) health-related quality of life (HRQOL) during years before death. If an individual, for example, was judged to be functioning at a 60% level (as rated on the investigator’s scale) for one year, he would be considered to have had 0.60 well-years of life.