ABSTRACT
In order to investigate risk factors for infectious diseases, a basic understanding of epidemiological methods is required. This is important to avoid misinterpretation when comparing the results of one study with another. For example, crude rates should not be used to compare populations of different structure without definition. Similarly, it is not appropriate to draw population-related conclusions from studies of limited size and power; this is always dangerous! Definitions can be summarized as follows:
Epidemiology-The study of disease in relation to populations. All findings must relate to a defined population. Epidemiology relates the pattern of disease to the population in which it occurs and requires study of both diseased and healthy persons. For epidemiology, incidence and prevalence rates form the basis for comparison between defined population groups.
