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The Clinical Research Glossary was developed by the Multi Regional Clinical Trials (MRCT) Center of Brigham and Women's Hospital and Harvard. Click on any glossary term to learn more about it on the MRCT website.

Glossary Words

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adverse event

Any health problem that happens during the study.

adverse reaction

A health problem that happens during the study and is possibly caused by the study treatment.


Remove, change, or hide personal details to protect participant privacy.


A group of participants in a research study who all receive the same study treatment.


Information that is collected and analyzed from a study participant.


baseline assessment

Information that is collected and analyzed from a study participant at the start of a study.

blood draw

Taking a sample of blood by using a needle.


clinical benefit

A health change that researchers measure to find out if the study treatment helps the study participants.

clinical research

A controlled way to study health and illness in people.

clinical trial

A way to study new drugs, devices and treatments to see if they are safe and work in people.


A group of participants who are similar to each other.

Computerized Tomography (CT) Scan

Pictures of the inside of a person’s body taken by a machine that uses a type of radiation.


Protecting personal information from people who should not have access.

A document used to explain the details of the research study.

control group

People in a study who do not receive the treatment or do not have the condition being studied.



Information collected from or about people taking part in a research study.


To stop a study treatment or stop being a participant in the study.

double-blind study

A study that is set up so that participants do not know which study treatment they are getting, and researchers do not know either.



How well a study treatment works in the study.

eligibility criteria

The reasons a person can be included in, or excluded from, a study.


A measure of the expected effect of the study treatment.


Agree to join a study as a study participant.

exclusion criteria

A list of reasons a person cannot be included in a study.


healthy volunteer

A study participant who does not have a disease or condition, including the one being studied.


inclusion criteria

A list of requirements a person must meet to take part in a study.

The process of learning and discussing the details of a research study before deciding whether to take part.


A way to give a fluid into a vein of a study participant.

institutional review board (IRB)

A team of people who review studies to protect the rights and welfare of study participants.


A treatment given in a study.

investigational product

A drug, device, vaccine or other treatment being tested in a study.


A person who leads a research study.


Magnetic Resonance Imaging (MRI)

Pictures of the inside of a person’s body that are taken by a machine using strong magnets and radio waves.

multicenter trial

A study that takes place at more than one research center.


non-inferiority trial

A study to test if a study treatment works about as well as another treatment.


observational study

A study that collects health information about study participants without changing their medical care.


A description of the overall results of the study.

outcome measure

How the endpoints of the study are measured.


Pharmacokinetic Study (PK study)

A study that measures what happens to a drug in a person’s body over time.


A step in the overall clinical research process to test a new drug, device, or treatment.

preclinical study

A study to test a treatment in the lab or in animals before testing it in people.


A complete description of the research plan and procedures.



A list of questions for study participants to answer as part of the study.



A way to use chance to place study participants into different study treatment groups.


side effect

A health problem that is likely caused by an approved treatment.

single-blind study

A study that is set up so that participants do not know which study treatment they are getting.

standard of care

Treatment usually given to patients for an illness.

study design

The way a study is set up to answer the study question.

study participant

A person who joins a research study.

study population

All the participants in a study.

superiority trial

A study to test if a study treatment works better than another treatment.



To stop being a participant in a study.



Pictures of the inside of a person’s body taken using radiation.

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