Epidemiology

Epidemiology is often described as the basic science of public health and it is concerned with the frequency and pattern of health events in a population. Epidemiological information is required for helping prevent illness, managing patients and public health planning.

A key feature is the measurement of the incidence of disease in relation to the population ‘at risk’. The population at risk is the group of people, healthy or sick, who would be counted as cases if they had the disease being studied. In concluding the 'risk', researchers calculate the level of increased risk according to their findings. Because many factors cannot be controlled in epidemiology studies, any perceived increased risk must be carefully considered to determine whether it truly represents an increase in risk or whether it is due to other factors.

For example, in a study investigating the link between heart disease and alcohol consumption, smoking would be a ‘confounding factor’ because smoking is also associated with both heart disease and alcohol consumption. Therefore, it could be unclear how much any risk of heart disease resulted from alcohol consumption and how much resulted from smoking.