This module focuses on case-control studies, which is one of the best known epidemiological study designs. Case-control studies are particularly useful when you don’t have the luxury of waiting for a long follow-up period to conclude. In this module, you will learn the key elements of case-control study design, and you will learn how to estimate the appropriate measure of association when presented with data from a case-control study.

Cohorts were ancient Roman military units, but in modern epidemiology the word “cohort” is used to describe a group with a shared characteristic. In cohort studies, we follow groups of people over time, we collect data on their exposure and outcome, and try to estimate whether there is an association between the group-defining characteristic and the outcome of interest. In this module, you will learn how to design such a study, the kind of problems which may arise and how it compares with case-control studies. You will also learn about nested case-control and case-cohort studies, which allow us to harness the advantages of cohort studies in more efficient ways. By the end of the module, you will be able to choose the best study design in a variety of contexts.

Randomised controlled trials are often seen as the gold standard of epidemiological research, especially in clinical settings, and in this module you will learn why. You will learn the main design features of randomised clinical trials, why they are so important, and the difficulties and limitations in applying these principles in real life. By the end of this module, you will know how to design a randomised clinical trial and how to decide which is the best analytical approach for the data you have obtained.