Introduction to Epidemiology for the Health Sciences

A fundamental problem in descriptive epidemiology is how to make meaningful and robust comparisons between different populations, or within the same population over different periods. The problem has several dimensions. First, the data we have to work with (e.g. incident and prevalent cases, and deaths) is rarely usable in its raw form. We must therefore transform it in some way before undertaking the comparison itself. Second, our data usually tells us about fundamentally different attributes of the populations we are seeking to compare. If we are only ever interested in comparing any one of these attributes at a time (mortality, for example), then one of several simple and well-established transformations is all that is typically required. Increasingly, however, epidemiologists are being asked to bring these attributes together into more integrated and meaningful comparisons.