Your Guide to Understanding Common Research Terms

Jun 7, 2019 | Brianna N. Tranby | @briannatranby

HLHS Mayo - doctor and patient

                             Demystifying Clinical Trials -- Part 2

The clinical research world can sometimes seem confusing. Research teams have many people in different roles, and they may use words that are unfamiliar to people outside of research work.

The guide below defines some commonly used words and phrases. Let us know in the comments below or on our Facebook, Twitter, or Instagram pages if you’d like definitions of other words or parts of the research process!


Accrual – the number of subjects who have completed or are actively in the process of completing a study. The accrual goal is how many subjects are needed to finish the study (2).

Adverse event (AE) – a negative symptom or experience encountered by an subject during the course of a clinical trial. Adverse events can be expected or unexpected.

Assent – a minor child’s affirmative agreement to participate in a clinical trial. Failure to object may not be taken as assent.

Clinical research coordinator – a study team member who manages the day-to-day study tasks as directed by the principal investigator. (3)

Consent form – a document explaining all relevant study information to assist the study subject in understanding the expectations and requirements of participating in the trial. This document is presented to and signed by the study subject.

Control arm/group – a comparison group of study subjects who are not treated with the investigational agent. The subjects in this group have the same disease or condition under study, but receive either a different treatment, no treatment, or a placebo.

Data – the objective information gathered during a research study that is used to determine the results of the study.

De-identification – the process of removing identifiers (personal names, dates, social security numbers, etc.) that directly or indirectly point to a person, and removing those identifiers from the data. De-identification of protected health information is essential for protecting patient privacy (4).

Enroll/Enrollment – the process of an eligible participant signing a consent form and voluntarily agreeing to participate in a research study (2).

Ethics committee – an independent group of both medical and non-medical professionals who are responsible for verifying the integrity of a study and ensuring the safety, integrity, and human rights of the study participants.

Food and Drug Administration (FDA) – the agency within the Department of Health and Human Services (DHHS) that enforces public health laws related to research conduct.

Greater than minimal risk – the research involves more than minimal risk to subjects (2).

Health Insurance Portability and Accountability Act of 1996 (HIPAA) – required the Department of Health & Human Services to develop regulations protecting the privacy and security of certain health information (5). The HIPAA Privacy Rule established the conditions under which health information may be used or disclosed by approved entities for research purposes (6).

Hypothesis – a specific, clear, and testable proposition or prediction about the possible outcome of a scientific research study (7).

Informed consent – the process of discussing a clinical trial that goes beyond signing the consent form. The discussion should provide sufficient information so that a subject can make an informed decision about whether or not to enroll in a study, or continue participation in a study. Informed consent is a voluntary agreement to participate in research, and should be an ongoing conversation throughout a subject’s entire time in the study (8).

Investigational New Drug Application (IND) – the process through which an investigator requests the FDA to allow human testing of a new drug.

Institutional Review Board (IRB) – an independent group of professionals designated to review and approve the clinical protocol, informed consent forms, study advertisements, and patient brochures to ensure that the study is safe for human participation. It is also the IRB’s responsibility to ensure that the study adheres to the FDA’s regulations.

Minimal risk – the probability that harm or discomfort anticipated in the research study are not greater than those encountered in daily life or during routine physical examinations (2).

National Institutes of Health (NIH) – agency within DHHS that provides funding for research, conducts studies, and funds multi-site national studies.

Protected Health Information (PHI) – individually identifiable health information. HIPAA provides federal protections for personal health information and gives patients more control over their health information. It also sets boundaries for how entities and institutions can use and release health records (9).

Placebo – an inactive substance designed to resemble the drug being tested. It is used as a control to rule out any psychological effects testing may present. Most advanced clinical trials include a control group that is unknowingly taking a placebo.

Principal Investigator – the primary individual responsible for conducting a clinical trial and adhering to federal regulations, institutional policies, and IRB regulations (2).

Protocol – a detailed plan that sets out the objectives, study design, and methodology for a clinical trial. A study protocol must be approved by an IRB before research may begin on human subjects.

Randomization – study participants are assigned to groups in such a way that each participant has an equal chance of being assigned to each treatment or control group. Since randomization ensures that no specific criteria are used to assign any patients to a particular group, all the groups will be equally comparable.

Research – systematic investigation designed to develop or contribute to generalizable knowledge.

Standard treatment/Standard of care – the currently accepted treatment or intervention considered to be effective in the treatment of a specific disease or condition.

Statistical significance – the probability that an event or difference was occurred by chance alone. In clinical trials, the level of statistical significance depends on the number or participants studied and the observations made, as well as the magnitude of differences observed.

Subject/Participant – a patient or healthy individual participating in a research study.

Treatment arm/group – a group of study subjects who are treated with the investigational agent.

Visit schedule/Test schedule – the number, frequency, and type of exams, tests, and procedures that research subjects will be expected to undergo during the study. Some visits may be the same as normal clinical care visits, while others may be required just for the purpose of collecting data for the research study.


Definitions taken from unless otherwise cited.










The Todd and Karen Wanek Family Program for Hypoplastic Left Heart Syndrome (HLHS) is a collaborative network of specialists bonded by the vision of finding solutions for individuals affected by congenital heart defects including HLHS. The specialized team is addressing the various aspects of these defects by using research and clinical strategies ranging from basic science to diagnostic imaging to regenerative therapies. Email the program at to learn more.

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