What are the two types of epidemiology?

Answer 1

There are many ways to classify the sub-fields of epidemiology and to describe the major types of epidemiological studies, one way to do so is as follows:

1) Descriptive Epidemiology - This is often done to explain the burden of disease. It does not require a comparison group. Descriptive epidemiology studies include cross-sectional studies, registries, and some ecological studies. Descriptive epidemiology can be used to answer questions like "What is the prevalence of type II diabetes in San Antonio?", "What was the incidence of new HIV infections in the US from 2010 to 2015?", or "What proportion of nurses smoke tobacco in the state of Colorado?".

2) Analytic Epidemiology - This is often done for etiological purposes (e.g., to attempt to explain causative properties of disease). Analytic epidemiology requires a COMPARISON GROUP. Study designs in Analytic epidemiology include the Case-Control study, Cohort Study, and a Randomized Controlled Trial (RCT). Analytic epidemiology can answer questions like "Is food X associated with disease Y?", "Does drug X reduce the risk of disease Y?", or "Does smoking increase the risk of disease Y?".