Blinded studies are done so that neither the researchers' nor the participants' expectations about the experimental treatment can influence the study results. In a "single-blinded" study, the participants do not know whether they are in an experimental group or a control group. In a "double-blinded" study, neither the participants nor the researchers know which participants are in which group.
A clinical trial is a research study designed to test the safety and/or effectiveness of drugs, devices, treatments, or preventive measures in humans. Clinical trials can usually be divided into four categories or "phases
In a particular study, researchers may divide participants into two groups — an "experimental group" and a "control group." The experimental group is given the experimental treatment under study, while the control group may be given either the standard treatment for the illness or a placebo
. At the end of the study, the results of the two groups are compared to determine the effectiveness of the experimental treatment.
Study participants in the experimental group receive the drug, device, treatment, or intervention under study. In some studies, all participants are in the experimental group. In "controlled studies," participants will be assigned either to an experimental group or to a control group
FDA (Food and Drug Administration)
The FDA is the U.S. government agency that enforces laws about the manufacturing, testing, and use of drugs and medical devices. The FDA must approve a drug for marketing before it is made commercially available to the public.
A human subject is a volunteer participant in a research study.
Informed consent is the participant's agreement to be in a study after being fully informed about what participating will involve. Informed consent begins with a discussion between the researchers and the prospective participants about some or all of the following information:
- The purpose of the study
- The procedures involved
- The risks of participating in the study
- The benefits of participating in the study
- How long the study will last
- How the participant's confidentiality will be protected
- What will happen if the study causes harm to the participants
- That participation is voluntary
- That participants are free to withdraw from the study at any time.
Based on this discussion, participants are asked to sign a consent form that includes this same important information in writing. Prospective study participants can take the consent form home to discuss it with family and friends before signing it. Once the form is signed, participants are given a copy of the signed consent form so that they can review it and ask questions of the researchers at any time before, during, and after the study.
Institutional Review Board (IRB)
An IRB is the committee that is given the responsibility by an institution to ensure the protection of the safety, rights, and welfare of the human subjects in that institution's research studies. At the University of Washington, the IRB is called the "Human Subjects Review Committee."
Investigational or experimental device
An investigational or experimental device is a medical device (such as an artificial heart valve or a screw used to hold bones together) that has not yet received approval from the U.S. Food and Drug Administration (FDA) for marketing.
Investigational or experimental drug
An investigational or experimental drug is a drug that is not yet approved for marketing — and is not commercially available.
A placebo is an inactive substance that may look like medicine but contains no medicine — it is often a "sugar pill" with no treatment value. In some studies, the participants in a control group may be given a placebo.
The principal investigator is the person in charge of carrying out a study.
The protocol of a research study explains what will be done, when, how, and why. A particular study may be done by several researchers around the nation or around the world. If each researcher follows the same protocol, information from all of the researchers can be combined and compared at the end of the study.
Random assignment is assignment by chance, like flipping a coin or pulling numbers out of a hat. This method is sometimes used to determine which study participants are assigned to the experimental group and which are assigned to the control group.
The sponsor is the company, research institution, group, foundation, or government agency that funds a research study.