ABSTRACT
The most commonly used measures of disease frequency are incidence and prevalence. The determination of an incidence rate requires a period of observation, which may be short or long depending on the natural history of the disease. The design of a study to measure the incidence of an infectious disease is about as simple and straightforward as anything can be in epidemiology. Dental diseases are common in most assemblages of human remains and include dental caries, teeth lost antemortem, abscesses, and periodontal disease. The actual form of the study varies according to the circumstances, but considers a factory where some workers are exposed to a dust thought to give rise to a disease of the lungs. The prevalence is then simply the number with the disease divided by the number in the study population. The prevalence of osteoarthritis among the dead is determined by counting the number who was allocated the disease in the first stage of the procedure.
