Script:
An epidemiologist has been invited to speak to students in a public health class. Listen to part of the talk.
Epidemiology is the field of medicine that deals with epidemics outbreaks of disease that affect large numbers of people. As an epidemiologist, I look at factors involved in the distribution and frequency of disease in human populations.
For example, what is it about what we do or what we eat, or what our environment is, that leads one group of people to be more likely—or less likely—to develop a disease than another group of people? It′s these factors that we try to identify.
We use statistical analyses, field investigations, and a range of laboratory techniques. We try to determine the cause and distribution of a disease. We also look at how quickly the disease spreads—and by what method—so we can implement measures to control and prevent the disease. Some epidemiologists concentrate on communicable diseases, like tuberculosis and AIDS. Others focus on the growing epidemics in cancer, diabetes, and heart disease.
We gather data in a variety of ways. One way is through what we call descriptive epidemiology, or looking at the trends of diseases over time, as well as ... uh ... trends of diseases in one population relative to another. Statistics are important in descriptive epidemiology, because numbers are a useful way to simplify information.
A second approach is observational epidemiology, where we observe what people do. We take a group of people who have a disease and a group of people who don′t have a disease. We look at their patterns of eating or drinking and their medical history. We also take a group of people who’ve been exposed to something—for example, smoking—and a group of people who haven′t, and then observe them over time to see whether they develop a disease or not. In observational epidemiology, we don’t interfere in the process. We just observe it.
A third approach is experimental epidemiology, sometimes called an intervention study. Experimental research is the best way to establish cause-and-effect relationships between variables. A typical experiment studies two groups of subjects. One group receives a treatment, and the other group—the control group—does not. Thus, the effectiveness of the treatment can be determined. Experimental research is the only type of research that directly attempts to influence a particular variable—called the treatment variable—as a way to test a hypothesis about cause and effect. Some examples of treatments that can be varied include the amount of iron or potassium in the diet, the amount or type of exercise one engages in per week, and the minutes of sunlight one is exposed to per day.
The Health Research Institute, of which I am the director, is mostly involved in experimental studies—I say mostly because we study treatment and non-treatment groups and then compare the outcomes. However, we do collect and study various types of data in any given year. From these different approaches —descriptive, observational, and experimental we can judge whether a particular factor causes or prevents the disease that we’re looking at.