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Commonly Used Terms - Definitions

Blinded studies
A blinded study is one in which the subject and/or investigator are unaware of what trial product a subject is receiving. 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.

Clinical trial
A clinical trial refers to a carefully designed and controlled research study in which one or more human subjects receive a drug or device for the purpose of determining/testing 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". The terms "clinical trial" and "clinical study" are synonymous.

Control group
Participants in a control group are used as a standard for comparison. For example, a particular study 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, a placebo, or no treatment. At the end of the study, the results of the two groups are compared.

A product's ability to produce beneficial effects on the course or duration of a disease.

Experimental group
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 on 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.

Human subject
A human subject is a volunteer participant in a research study, either as a recipient of the test article or as a control.

Informed consent
Informed consent is the participant's written agreement to be in a study after being fully informed about what participation will involve. Informed consent begins with a discussion between the researchers and the prospective participants. The discussion includes important information about the research study such as:

  • What is the purpose of the study?
  • What is involved? What types of procedures will be performed?
  • What are the risks of participation?
  • What are the benefits of participation?
  • How long will the study take?
  • Will my confidentiality be maintained? How?
  • What happens if I get sick or hurt during the study:
  • Why do I have to participate in the study? Is it voluntary?
  • Can I quit at any time?
  • Do I have to ask all of my questions at one time?

Institutional Review Board (IRB)
An IRB is a committee, comprised of medical, scientific and non-scientific members, whose responsibility it is to review all research projects involving human subjects being considered by an institution. The primary purpose of the IRB review is to assure the protection of the safety, rights and welfare of the human subjects. At the University of Pennsylvania, the IRB is called the "Committee on Studies Involving Human Beings."

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/device
A drug or device being tested or used in a clinical trial, including a product being used in a way different from its approved form, for an unapproved indication/use, or to gain further information about an approved use.

A placebo is an inactive substance. In blinded studies it is usually made to look like the active product. It may be considered a "sugar pill".

Principal investigator
The principal investigator is the individual responsible for the conduct of a clinical trial at a trial site.

The protocol is the formal design or action plan of a research study that describes what will be done, when, how, and why.

Random allocation
Random allocation is assignment by chance to determine who is in the experimental group and who is in the control group.

The sponsor is the company, research institution, group, foundation, or government agency that takes responsibility for the initiation, management and/or financing of a clinical trial