Search the Research Glossary

25 terms found

Adverse eventGeneral Clinical Research

Any unwanted health change that happens to a volunteer during a study, whether or not it is caused by the thing being studied.

Example: A volunteer reports a headache after a study visit. The team records it as an adverse event, even if the cause is unclear.

ArmRandomized Studies

A group of volunteers in a study who all follow the same plan.

Example: A study might have two arms: one group tries a new approach and the other follows the usual approach.

BlindingPlacebo-Controlled Studies

Keeping certain people from knowing which group a volunteer is in, so expectations do not shape the results.

Example: In a single-blind study, volunteers do not know their group. In a double-blind study, the study team does not know either.

CohortObservational Research

A group of people who share something in common and are followed over time.

Example: Researchers follow a cohort of adults born in the same year to see how sleep habits change with age.

Control groupRandomized Studies

The group that does not receive the approach being tested, used as a point of comparison.

Example: If the tested group improves more than the control group, researchers have a clue the approach made a difference.

Crossover designRandomized Studies

A setup where each volunteer tries more than one approach, one after another, in a planned order.

Example: Volunteers try approach A for four weeks, take a break, and then try approach B for four weeks.

Dose escalationEarly-Phase Research

Slowly increasing the amount of something being studied across small groups to learn how much is well tolerated.

Example: The first small group receives a low amount. Only after a safety review does the next group receive a slightly higher amount.

Eligibility criteriaGeneral Clinical Research

The list of requirements a study uses to decide who can and cannot take part. Each study sets its own list.

Example: A study might require volunteers to be between 18 and 65 and to not have taken part in another study recently.

EndpointGeneral Clinical Research

The specific result a study measures to answer its main question.

Example: In a sleep study, the primary endpoint could be the average number of hours slept per night.

Ethics committeeGeneral Clinical Research

An independent group that reviews a study plan to protect the rights, safety, and wellbeing of volunteers. In the US it is often called an IRB.

Example: Before a study can begin, the ethics committee reviews the consent form to make sure it is clear and honest.

Exclusion criteriaGeneral Clinical Research

The part of the eligibility list that describes reasons a person cannot join a particular study.

Example: Being pregnant is a common exclusion criterion in early studies because less is known about safety.

First-in-human studyEarly-Phase Research

The first time a new approach is tried in people, usually with a very small group and close monitoring.

Example: After lab research, a first-in-human study checks basic safety in a handful of healthy volunteers.

Healthy volunteerEarly-Phase Research

A person without the condition being studied who takes part to help researchers learn about safety or how the body responds.

Example: Many early-phase studies invite healthy volunteers to help measure how the body processes a substance.

Informed consentGeneral Clinical Research

The ongoing process of learning about a study, asking questions, and freely deciding whether to take part. You can change your mind at any time.

Example: Before joining, a volunteer reads the consent form, asks the team questions, and takes time to decide.

Longitudinal studyObservational Research

A study that collects information from the same people repeatedly over a long period.

Example: A longitudinal study might send the same questionnaire to volunteers every year for ten years.

Observational studyObservational Research

A study where researchers watch and record what happens without assigning volunteers to a specific approach.

Example: Researchers track daily step counts to see how activity relates to mood, without asking anyone to change habits.

PhaseEarly-Phase Research

A stage of testing. Earlier phases focus on safety in small groups, while later phases involve more people and compare results.

Example: Phase 1 studies are usually small and focus on safety. Phase 3 studies are much larger.

PlaceboPlacebo-Controlled Studies

An inactive look-alike, such as a sugar pill, used so researchers can compare it with the approach being tested.

Example: Half the volunteers receive the tested option and half receive a placebo that looks the same.

Placebo effectPlacebo-Controlled Studies

A real change people notice simply because they expect something to help.

Example: Some volunteers taking a placebo report feeling better, which is why comparison groups matter.

Principal investigatorGeneral Clinical Research

The person who leads a study at a specific location and is responsible for how it is run.

Example: Questions about study visits are often directed to the principal investigator or the study coordinator.

ProtocolGeneral Clinical Research

The detailed written plan for a study: its purpose, who can join, what happens at each visit, and how results are measured.

Example: The protocol explains that volunteers attend six visits over three months.

RandomizationRandomized Studies

Assigning volunteers to groups by chance, like a coin flip, so the groups are fair to compare.

Example: A computer program randomly places each new volunteer in either group A or group B.

Retrospective studyObservational Research

A study that looks back at information that was already collected in the past.

Example: Researchers review anonymous records from the last five years to look for patterns.

Washout periodPlacebo-Controlled Studies

A break between parts of a study so the effects of one approach fade before the next begins.

Example: In a crossover study, volunteers take a two-week washout period before switching approaches.

WithdrawalGeneral Clinical Research

Choosing to stop taking part in a study. Volunteers can withdraw at any time for any reason.

Example: A volunteer decides the visit schedule no longer works and lets the team know they are withdrawing.