Japanese and German men, for example, generally have higher suicide rates than the U.S. men, but the rates rise at older ages in all three countries. In Canada, reported suicide rates are highest in the young adult years, but the likelihood of suicide rises again in the oldest age group. Teenagers and young adults, on the other hand, face a higher risk of dying or being injured in an automobile crash than people in other age groups. A Rhode Island study in the 1980s showed, for example, that men ages 15 to 34 and women ages 15 to 24 were much more likely to be hospitalized or killed in an automobile crash than people in other age groups. A male's risk of being a homicide victim is much higher in the United States than in other populous industrialized countries, as shown in Figure 2.
Descriptive epidemiology is a two-step process.
The first step involves the rather mechanical task of amassing all the facts about a situation or problem. The second is the more contemplative step of conceiving a plausible explanation for why the situation exists. This second phase, known as hypothesis formulation, involves examining all the facts and asking questions from different perspectives. It is the bridge between descriptive and analytic epidemiology. But before testing a hypothesis, researchers must describe the problem in standard terms.