Why sickness and death rates do not move parallel to one another over time

Scholars sometimes claim that mortality and morbibity move papallel to one another over time. Using case studies from nineteenth-century England and Wales, this essay plots actual relationships in historical populations and explores why parallelism should not be expected. The implication of finding that mortality and morbidity chart independent courses is that they are either shaped by different factors or by the same factors operating in different ways. Hence morbidity should not be expected to be controlled by policies formulated to control mortality.