The above theoretical discussions have been useful in clarifying that one needs to use a basic epidemiological approach in thinking about the relationship between trends in different aspects of health. Mortality is a dynamic process that removes people from the population at a faster or slower rate over time. The number or proportion of people who are not healthy in a population is an indicator of population health—or a stock measure—at a point in time. This indicator is affected by a number of dynamic processes: the age-specific onset rates of unhealthy conditions, the rate of health deterioration of people with these conditions, and the likelihood that Annu. Rev
