Glossary of Terms

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What is a placebo?

A placebo is an inactive pill, liquid, or powder that is made to be physically indistinguishable (it looks and tastes identical) from the actual drug being studied. In some studies, participants may be assigned to take a placebo rather than the study medication.

What is a control group?

A control group is the group of participants that receives standard treatment or a placebo. The control group may also be made up of healthy volunteers. Researchers compare results from the control group with results from the experimental group to find and learn from any differences.

What is a blind study?

In many clinical trials, one group of patients will be given an experimental drug or treatment, while a control group is given either a standard treatment for the illness, a placebo, or no treatment at all. In a "blinded" or "masked" study, participants do not know whether they are getting the drug being tested, or whether they are in the control group. The goal is to prevent the so-called "placebo effect" from influencing the results of the experiment. The placebo effect is the phenomenon of patients feeling better simply because they think they are receiving a helpful drug or treatment.

What is a double-blind study?

Sometimes, clinical trials are "double-blind" or "double-masked." That means that neither the participants, nor the study staff members, know who is receiving the experimental drug and who is in the control group. Studies are performed in this way so that neither the patients' nor the doctors' expectations about the experimental drug can influence the observations and results.

What is a protocol?

A protocol is a plan that details what researchers will do during a study. It describes what types of people are eligible to participate in the study; determines the schedule of tests, procedures, medications, and dosages; and sets the length of the study. Every study must have a protocol. The protocol includes information on how researchers will work to keep participants safe.

What is a principal investigator?

The Principal Investigator (PI) is the lead scientist responsible for conducting and supervising a clinical trial and for protecting the rights, safety, and welfare of the participants enrolled in the research.

What is a sub-investigator?

The Sub-Investigator may perform all or some of the PI functions, but they do not accept primary responsibility for the research study. The Sub-Investigator is under the supervision of the PI and is responsible for performing study–related procedures and /or to make important study-related decisions in compliance with the ethical conduct of the study.

What is an investigational product?

An Investigational Product is a preventative (vaccine), a therapeutic (drug or biologic), device, diagnostic or palliative used in a clinical trial. An Investigational Product may be an unlicensed product or a licensed product when used or assembled (formulated or packaged) differently from the approved form, when used for an unapproved indication, or when used to gain further information about an approved use.