Epidemiology is the branch of medical science that deals with the factors that determine the presence or absence of diseases. Epidemiology is the study and analysis of the distribution, patterns and determinants of health and disease conditions in defined populations. It is a cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare.

Why do we focus on this : The purpose of epidemiology research is to understand what risk factors are associated with a specific disease, and how disease can be prevented. Epidemiological research helps us to understand how many people have a disease, if those numbers are changing, and how the disease affects our society or our economy. Epidemiological information is used to plan and evaluate strategies to prevent illness and as a guide to the management of patients who are already suffering.