Clinical trials follow strict scientific guidelines. These guidelines deal with many areas, including the study''s design, who can be in the study, and the kind of information people must be given when they are deciding whether to participate. Every trial has a chief investigator, who is usually a doctor. The investigator follows a study action plan, called a protocol. This plan explains what the trial will do, how, and why. For example, it states:
- How many people will be in the study.
- Who is eligible to participate.
- What medical tests they will have and how often.
- How long each participant will be in the study.
Every research center which takes part in the trial uses the same protocol. This assures that information from all centers can be combined and compared.