How Medical Facts Are Developed: Why Some Are More Potent Than Others

Medical scientists view the reality of health and disease in three ways. The most ancient, which was used by Egyptian physicians more than four thousand years ago, is the systematic observation of those who are sick. Through the intensive study of the course of illness in their patients, physicians through the ages have gained knowledge of disease and developed ways of treating it. This simple type of research, the case study, is the foundation of the healing arts and the inspiration for most of the new concepts in medical science.

Beginning in the late nineteenth century, a second type of research, the laboratory experiment, provided a powerful means of testing the concepts that physicians derived from their observations of patients. Through the study of animals, of living tissues, of cells, and of disease-causing agents, laboratory investigators helped to transform medicine from a largely hit-or-miss art into an increasingly effective, science-based discipline.

The third kind of research, like the first, involves people. However, unlike the case study, which focuses on the sick individual, this third type of research deals with groups of people, both the sick and the well. Its most important tool is statistics, and since its early practitioners were concerned with epidemics of smallpox, typhoid, and other infectious diseases, it acquired the name epidemiology.

Epidemiologists study the characteristics of people—where they live, how they earn a living, what they eat, whether or not they smoke, whether they are fat or thin, what illnesses their parents had; in short, all of the countless circumstances and habits that keep them in good health or propel them into illness.

Link