A study reports that smokers face a relative risk of dying from lung cancer 24 times higher than non-smokers, and a relative risk of only 1.4 times higher for dying of heart disease. How important are these differences? If you have no idea, then the course Measuring Risk in Epidemiology is for you. The course introduces key measures of risk, shows how they’re calculated, and discusses how to interpret them when you encounter them in reports and news stories. This is part of a nine-part series on epidemiology.