 The most commonly used metric is called “quality of life”—every health improvement, whatever else it accomplishes, incrementally improves the individual’s quality of life. Given that a health improvement is potentially either quantitative or qualitative (extending life or improving life), it is necessary to bring these two facets into a single measure (called, generically, a summary health measure). A common way of doing this is in terms of the econometric concept of quality-adjusted life year or QALY. Every health improvement produces a health state with an expected longevity (the number of years left to live) and level of functioning (the quality of living in that health state). These can be metrically joined into a single score by using the common metric of years lives and discounting the value of a year lived in a particular health state by the quality of life value of living in that state. If full health is represented by the value of 1, death by 0, then the quality of life values of all possible states of health a human can experience can be assigned a number between 1 and 0, and that number determines the quality of life impact of the health state on a person, in terms of some proportion of a full life year. The values for each state can be generated by a population ranking exercise (as was done in the Oregon example), by expert consensus, or by means of a variety of econometric “preference elicitation techniques” such as “standard gamble”, “willingness to pay” or “person trade off” (see Nord 1999 for the details of these techniques in the health domain).