There are five main categories of clinical trials and each targets a different, yet specific, element of the health care process.
Clinical trials are also sometimes classified as interventional or observational. Interventional trials expose new treatments and treatment methods to individuals of a chosen group in a controlled environment. Observational trials take a given health issue and assess that issue as it applies to a large group of people in a natural setting (e.g. students in a specific school district or residents of a geographical area).
The following links provide more information about clinical trials and how to participate: