One of the first steps in the epidemiologic framework is the
conduct of descriptive studies. Descriptive studies provide
information to understand the importance of injuries and to
describe potential causal factors behind them. Most of the
current information available to describe injuries has been
identified through injury surveillance systems.
Surveillance systems represent the systematic collection of data
on a disease. They identify the existing level of disease.
Over time they identify trends to show if diseases are increasing
or decreasing in incidence, and which are changing in their
distribution. This information is needed to identify emerging
problems and also to assess the effectiveness of measures to
control old problems. For more information, see Epidemiology for
the Uninitiated, Chapter 1.