Clinical research glossary
Plain-language definitions of the vocabulary used in clinical trials — the terms that appear in job adverts, protocols, training, and interviews. Free to read, no sign-up.
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A
- Academic research organization (ARO)An academic research organization is a university-based unit that provides trial services in a similar way to a CRO.
- Adaptive designAn adaptive design allows pre-planned changes to a trial based on data gathered while it runs — for example dropping a dose, re-estimating the sample size, or stopping early.
- AdherenceAdherence is how closely a participant follows the treatment regimen and the study requirements.
- Adverse event (AE)An adverse event is any unfavorable medical occurrence in a participant during a trial, whether or not it is thought to be caused by the study treatment.
- Adverse reaction (AR)An adverse reaction is an adverse event for which there is at least a reasonable possibility that the study treatment caused it.
- ALCOA+ALCOA+ is a memory aid for the qualities good trial data must have.
- Allocation concealmentAllocation concealment means the person enrolling a participant cannot know or predict which arm that participant will be assigned to.
- ArchivingArchiving is the secure, long-term storage of trial records after the trial ends, so they remain complete, readable, and retrievable.
- AssentAssent is the agreement of someone who cannot legally give consent — most often a child — to take part in research.
- AuditAn audit is a systematic, independent examination of trial activities and documents to judge whether they were carried out according to the protocol, SOPs, GCP, and regulation.
- Audit certificateAn audit certificate is a short document confirming that an audit took place, issued by the auditor.
- Audit trailAn audit trail is the secure, automatically generated record of who changed what, when, and why in an electronic system.
B
- BaselineBaseline is the measurement taken before treatment starts, used as the reference point for everything that follows.
- Belmont ReportThe Belmont Report is a 1979 United States report that set out three ethical principles for research with human participants: respect for persons, beneficence, and justice.
- Benefit–risk assessmentBenefit–risk assessment is the structured judgment of whether a treatment's likely benefits justify its known and potential harms in a defined population.
- BiasBias is any systematic error that pushes a trial's results away from the truth in a consistent direction.
- BiomarkerA biomarker is a characteristic that can be measured objectively as an indicator of a biological process, a disease state, or a response to treatment.
- BlindingBlinding means keeping who received which treatment hidden from some or all of the people involved.
C
- Case report form (CRF)A case report form is the structured record in which the data a protocol requires is reported to the sponsor for each participant.
- Causality assessmentCausality assessment is the judgment of whether the study treatment could have caused an adverse event.
- CDISC standards (CDISC)CDISC is the organization behind the data standards used to structure clinical trial data for exchange and submission.
- Centralised monitoringCentralised monitoring is remote analysis of the data flowing in from all sites, looking for patterns that suggest a problem.
- Certified copyA certified copy is a reproduction of an original record that has been verified — by signature or by a validated process — as having the same content and meaning as the original.
- Clinical data manager (CDM)A clinical data manager is responsible for the quality of a trial's data from capture through to database lock.
- Clinical equipoiseClinical equipoise is genuine uncertainty within the expert community about which of the treatments being compared is better.
- Clinical holdA clinical hold is an order from a regulatory authority to delay a proposed trial or suspend one already running.
- Clinical project manager (CPM)A clinical project manager owns the delivery of a trial: its timeline, budget, resourcing, and vendors.
- Clinical research associate (CRA)A clinical research associate monitors clinical trials on behalf of the sponsor or CRO.
- Clinical research coordinator (CRC)A clinical research coordinator runs the day-to-day operation of a trial at a site.
- Clinical study report (CSR)The clinical study report is the full written account of a completed trial: its design, conduct, results, and interpretation.
- Clinical trialA clinical trial is a research study in which people are assigned to an intervention according to a plan, in order to evaluate its effects on health outcomes.
- Clinical trial agreement (CTA (contract))A clinical trial agreement is the contract between the sponsor and the institution or investigator running the trial.
- Clinical trial applicationA clinical trial application is the submission requesting permission to run a trial in a given country or region.
- Clinical trial assistant (CTA)A clinical trial assistant supports a study team with the administrative backbone of a trial.
- Clinical trial management system (CTMS)A clinical trial management system is the operational software used to plan and track a trial: sites, contacts, visits, milestones, recruitment numbers, payments, and monitoring activity.
- Clinician-reported outcome (ClinRO)A clinician-reported outcome is an assessment made by a trained health professional that requires clinical judgment, such as rating the severity of a rash or scoring a neurological examination.
- Close-out visit (COV)The close-out visit is the final monitoring visit, held once all participants have finished and outstanding issues are resolved.
- ComparatorA comparator is whatever the investigational treatment is measured against.
- Computer system validation (CSV)Computer system validation is documented evidence that a system does what it is supposed to do, consistently and reliably.
- Concomitant medicationConcomitant medications are any other treatments a participant is taking alongside the study treatment.
- Confidentiality (in trials)Confidentiality in a trial means that a participant's identity and personal health information are protected and only shared with people who need them.
- ConfoundingConfounding happens when a third factor is linked to both the treatment and the outcome, making it look as though the treatment caused an effect it did not.
- Contract research organization (CRO)A contract research organization is a company a sponsor hires to run part or all of a clinical trial.
- Control groupThe control group is the arm a treatment is compared against, receiving a placebo, an existing standard treatment, or no additional treatment.
- Corrective and preventive action (CAPA)A CAPA is the structured response to a problem: correct what went wrong, and change something so it does not happen again.
- Critical to quality factors (CtQ)Critical to quality factors are the small number of things in a trial that, if they go wrong, would seriously undermine participant safety or the credibility of the results.
- Crossover designIn a crossover design each participant receives more than one of the treatments in sequence, so they act as their own comparison.
D
- Data cleaningData cleaning is the work of finding and resolving errors, gaps, and inconsistencies in trial data before analysis.
- Data integrityData integrity means trial data is complete, consistent, and accurate throughout its life, from first capture to final archive.
- Data management plan (DMP)The data management plan describes how a trial's data will be collected, checked, corrected, coded, and locked.
- Data monitoring committee (DMC)A data monitoring committee is an independent group of experts that periodically reviews accumulating safety, and sometimes efficacy, data from an ongoing trial.
- Database lockDatabase lock is the point at which a trial's data is declared final and further changes are prevented.
- Decentralised clinical trial (DCT)A decentralised trial moves some or all trial activity away from the traditional site, using telemedicine visits, home nursing, local laboratories, direct-to-participant shipping, and connected devices.
- Dechallenge and rechallengeDechallenge is what happens to a reaction when the suspected treatment is stopped or reduced; rechallenge is what happens if it is restarted.
- Declaration of HelsinkiThe Declaration of Helsinki is a statement of ethical principles for medical research involving people, first adopted by the World Medical Association in 1964 and revised many times since.
- Delegation of authority logThe delegation of authority log is the signed record of which trial tasks the principal investigator has delegated to which named staff, and from what date.
- Development safety update report (DSUR)A DSUR is the annual safety report a sponsor prepares for a product still in development.
- Dose escalationDose escalation is giving successively higher doses to successive small groups of participants, watching safety carefully at each step before moving up.
E
- Edit checkAn edit check is a rule programmed into the data system that flags a value which looks wrong.
- Electronic case report form (eCRF)An electronic case report form is a case report form completed in a validated electronic system rather than on paper.
- Electronic consent (eConsent)Electronic consent presents the consent information and captures the signature electronically, often with video, diagrams, or comprehension checks built in.
- Electronic data capture (EDC)Electronic data capture is the software system sites use to enter and submit trial data to the sponsor.
- Electronic patient-reported outcome (ePRO)An electronic patient-reported outcome is data reported directly by the participant through an app, device, or web form, with no clinician interpreting it.
- Electronic trial master file (eTMF)An electronic trial master file is a trial master file held in a validated electronic system.
- Eligibility criteriaEligibility criteria are the protocol's rules about who may take part.
- EndpointAn endpoint is a defined measurement used to judge whether a treatment had an effect.
- EnrolmentEnrollment is the point at which a person who has consented and met all eligibility criteria formally joins the trial.
- Essential documentsEssential documents are the records that, individually and together, allow a trial's conduct and its data quality to be evaluated.
- EstimandAn estimand is a precise statement of exactly what treatment effect a trial is trying to estimate, including the population, the outcome, and how events such as stopping treatment are handled.
- ExpectednessExpectedness is the judgment of whether an adverse reaction is already described in the product's reference safety information.
- Expedited reportingExpedited reporting is the fast-track submission of specific safety cases to regulators and, where required, to ethics committees and investigators.
- Exploratory endpointAn exploratory endpoint is a measurement collected to generate ideas rather than to prove anything.
F
- Form FDA 1572Form FDA 1572 is the statement an investigator signs for trials conducted under a US IND, committing to conduct the study according to the protocol and the applicable regulations.
- Form FDA 483A Form FDA 483 is the list of observations an FDA investigator leaves at the end of an inspection when they have seen conditions that may breach the law FDA enforces.
G
- Good Clinical Practice (GCP)Good Clinical Practice (GCP) is the international quality standard for designing, running, recording, and reporting clinical trials in people.
- Good Laboratory Practice (GLP)Good Laboratory Practice is the quality system for non-clinical safety studies — typically laboratory and animal work done before a treatment reaches people.
- Good Manufacturing Practice (GMP)Good Manufacturing Practice is the quality standard governing how medicines are produced, packaged, labeled, and controlled.
- Good Pharmacovigilance Practice (GVP)Good Pharmacovigilance Practice is the set of guidelines governing how safety information about medicines is collected, assessed, and reported, mainly after approval.
I
- ICH E6ICH E6 is the specific ICH guideline that sets out Good Clinical Practice.
- ICH E6(R3)ICH E6(R3) is the modernised revision of the GCP guideline, reorganized around a set of overarching principles plus annexes.
- Informed consentInformed consent is the process by which a person voluntarily agrees to take part in a trial after being given, and understanding, the information they need to decide.
- Informed consent form (ICF)The informed consent form is the written document a participant reads and signs to record their agreement to take part.
- InspectionAn inspection is an official review conducted by a regulatory authority of trial-related sites, documents, facilities, and records.
- Institutional review board / ethics committee (IRB / IEC)An IRB or independent ethics committee is a group, independent of the sponsor and investigator, that reviews a trial to protect the rights, safety, and wellbeing of participants.
- Intention-to-treat analysis (ITT)Intention-to-treat analysis includes every randomized participant in the group they were assigned to, regardless of what treatment they actually received or whether they completed the trial.
- Interactive response technology (IRT)Interactive response technology is the system that assigns participants to treatment arms and manages drug supply at sites.
- Interim analysisAn interim analysis is a planned look at trial data before recruitment and follow-up are complete.
- International Council for Harmonisation (ICH)The ICH is the body where drug regulators and the pharmaceutical industry agree common technical standards for medicines.
- Investigational new drug application (IND)An IND is the application a sponsor files with the FDA to begin testing a new drug in people in the United States.
- Investigational product (IP)The investigational product is the treatment being tested in a trial, including any placebo or comparator supplied for it.
- Investigational product accountabilityInvestigational product accountability is the documented tracking of every unit of study treatment from arrival at a site to its use, return, or destruction.
- Investigator siteThe investigator site is the hospital, clinic, or practice where participants are actually seen and trial procedures happen.
- Investigator site file (ISF)The investigator site file is the site's own collection of essential documents for a trial.
- Investigator-initiated trial (IIT)An investigator-initiated trial is a study designed and run by a clinician or academic group rather than by a company.
- Investigator's brochure (IB)The investigator's brochure is the sponsor's summary of everything known so far about the investigational product.
M
- MedDRAMedDRA is the standard medical dictionary used to code symptoms, diagnoses, and other medical events in regulatory data.
- Medical codingMedical coding in trials is the process of mapping free-text terms reported by sites onto standard dictionary terms.
- Medical monitorA medical monitor is a physician who provides medical oversight of a trial for the sponsor.
- Missing dataMissing data is information a trial planned to collect but did not obtain, from a single blank field to a participant's entire follow-up.
- MonitoringMonitoring is the sponsor's ongoing check that a trial is being run according to the protocol, GCP, and the applicable regulations.
- Monitoring planThe monitoring plan describes how a specific trial will be monitored: the mix of on-site, remote, and centralised activity, the visit frequency, and what will be reviewed at each.
- Monitoring visitA monitoring visit is a scheduled review of a site by the sponsor's monitor.
- Multicenter trialA multicenter trial runs the same protocol at more than one site, often across several countries.
N
- Non-inferiority trialA non-inferiority trial aims to show that a new treatment is not meaningfully worse than an existing one, within a pre-defined margin.
- Note to file (NTF)A note to file is a short, dated, signed memo placed in the study records to explain something that is not obvious from the documents alone.
O
P
- Parallel-group designIn a parallel-group design each participant is assigned to one arm and stays in it for the whole trial.
- ParticipantA participant is a person who takes part in a clinical trial, whether receiving the investigational product or a comparator.
- Patient registryA patient registry is an organized collection of data about people with a particular condition, exposure, or treatment, gathered over time for a defined purpose.
- Patient-reported outcome (PRO)A patient-reported outcome is any report of a participant's health status that comes straight from the participant.
- Per-protocol analysisA per-protocol analysis includes only the participants who followed the protocol closely enough, excluding major deviations and poor adherence.
- Pharmacovigilance (PV)Pharmacovigilance is the science and practice of detecting, assessing, understanding, and preventing harm from medicines.
- Pharmacovigilance associate (PV associate)A pharmacovigilance associate processes and reports safety information about a medicine.
- Phase I trialA Phase I trial is usually the first time a treatment is given to people.
- Phase II trialA Phase II trial looks for the first evidence that a treatment actually works, while continuing to study safety and dose.
- Phase III trialA Phase III trial is the large, confirmatory study designed to establish whether a treatment works and how safe it is, usually against a placebo or an existing standard.
- Phase IV trialA Phase IV trial takes place after a treatment has been approved and is on the market.
- PlaceboA placebo is a dummy treatment made to look, taste, and feel like the real one but without the active ingredient.
- Primary endpointThe primary endpoint is the single main measurement a trial is designed and sized to answer.
- Principal investigator (PI)The principal investigator is the person responsible for the conduct of a clinical trial at one site.
- Proof of concept (PoC)A proof-of-concept study asks whether a treatment shows the biological effect its developers expect, before committing to large and expensive trials.
- ProtocolThe protocol is the master plan for a clinical trial.
- Protocol amendmentA protocol amendment is a formal, documented change to an approved protocol.
- Protocol deviationA protocol deviation is any departure from what the approved protocol says should happen.
- PseudonymisationPseudonymisation replaces a participant's directly identifying details with a code, so that data can be analyzed without naming the person.
Q
- Quality assurance (QA)Quality assurance is the set of planned, systematic activities that give confidence a trial is being run and its data generated to the required standards.
- Quality by design (QbD)Quality by design means building quality into a trial while it is being planned, instead of trying to inspect it in afterwards.
- Quality control (QC)Quality control is the hands-on checking done within the trial process to verify that the work meets requirements.
- QueryA query is a formal question raised about a data point that looks missing, inconsistent, or implausible.
R
- RandomisationRandomization is assigning participants to trial arms by chance rather than by choice.
- Re-consentRe-consent is obtaining a participant's agreement again after important new information appears or the trial changes in a way that could affect their willingness to continue.
- Re-screeningRe-screening is screening someone again after an earlier screen failure, where the protocol permits it.
- Real-world evidence (RWE)Real-world evidence is evidence about a treatment derived from data collected outside conventional trials — electronic health records, claims data, registries, and devices.
- Reference safety information (RSI)Reference safety information is the specific, clearly identified section of a document — usually the investigator's brochure — used to decide whether a reaction is expected.
- Regulatory affairs associate (RA associate)A regulatory affairs associate prepares and manages the submissions a trial or a product needs from health authorities.
- Regulatory authorityA regulatory authority is the government body that authorizes trials and approves medicines in its territory.
- Regulatory submissionA regulatory submission is the dossier a company files asking an authority to approve a product for sale.
- Research fraudResearch fraud is the deliberate fabrication, falsification, or suppression of trial data or records.
- Results disclosureResults disclosure is the obligation to make a trial's summary results publicly available within a set time after it ends, whether the findings are positive or not.
- RetentionRetention is keeping enrolled participants engaged in a trial until they complete it.
- Risk-based monitoring (RBM)Risk-based monitoring concentrates monitoring effort where the risk to participants and to data reliability is greatest, rather than treating every site and every data point equally.
- Risk-based quality management (RBQM)Risk-based quality management is a structured way of identifying what could go wrong in a trial, deciding which of those risks matter most, and putting effort where the risk is highest.
- Root cause analysis (RCA)Root cause analysis is the process of working past the immediate error to the underlying reason it was possible.
- Run-in periodA run-in period is a defined stretch before randomization during which participants may take a placebo or a standard treatment.
S
- SAE reconciliationSAE reconciliation is the cross-check between the serious adverse events recorded in the clinical database and those held in the separate safety database.
- Safety databaseThe safety database is the dedicated system in which a sponsor records, assesses, and reports individual safety cases.
- Schedule of assessmentsThe schedule of assessments is the table in a protocol showing every visit and exactly which procedures happen at each one.
- Screen failureA screen failure is a person who consented and was screened but did not meet the eligibility criteria and so was not enrolled.
- ScreeningScreening is the set of assessments done after consent to check whether a person actually meets the eligibility criteria.
- Seamless designA seamless design combines what would normally be two separate trial phases into one continuous study, such as running dose selection and confirmation under a single protocol.
- Secondary endpointSecondary endpoints are additional pre-specified measurements that support or add context to the primary result.
- Selection biasSelection bias occurs when the people in a study, or in each arm, differ systematically in ways that affect the outcome.
- Serious adverse event (SAE)A serious adverse event is an adverse event that meets at least one defined seriousness criterion: it results in death, is life-threatening, requires or prolongs hospitalization, causes persistent or significant disability or incapacity, or is a congenital anomaly or birth defect.
- Serious breachA serious breach is a departure from the protocol or from GCP that is likely to significantly affect participant safety or physical or mental integrity, or the reliability of the trial's results.
- SeriousnessSeriousness is the regulatory classification of an adverse event based on its outcome, not on how intense it feels.
- SeveritySeverity describes how intense an adverse event is, usually graded as mild, moderate, or severe, or on a scale such as CTCAE in oncology.
- Signal detectionSignal detection is the systematic search for new information suggesting a possible causal link between a medicine and an event that was not previously known.
- Site activationSite activation is the point at which a site is formally permitted to start screening and enrolling participants.
- Site initiation visit (SIV)The site initiation visit is the meeting that formally opens a site for recruitment.
- Source dataSource data is the information in source documents: the original observations, measurements, and records needed to reconstruct and evaluate a trial.
- Source data review (SDR)Source data review is reading the site's records as a whole to judge whether the trial is being run properly — not just whether individual values were transcribed correctly.
- Source data verification (SDV)Source data verification is comparing what is reported in the case report form against the original source documents to confirm it matches.
- Source documentA source document is the original place where a piece of trial information was first recorded.
- SponsorThe sponsor is the organization or person who takes responsibility for starting, managing, and financing a clinical trial.
- Sponsor-investigatorA sponsor-investigator is one person who both initiates a trial and personally conducts it, taking on the duties of both roles.
- Standard operating procedure (SOP)A standard operating procedure is a written instruction describing how an organization performs a recurring task consistently.
- Statistical analysis plan (SAP)The statistical analysis plan sets out in detail how a trial's data will be analyzed.
- Statistical powerStatistical power is the probability that a trial will detect a real effect of a given size if one exists.
- Stopping ruleA stopping rule is a pre-specified condition under which a trial, or part of it, will be halted.
- StratificationStratification is randomizing separately within groups defined by an important characteristic, such as disease severity, age band, or site.
- Sub-investigator (Sub-I)A sub-investigator is a qualified member of the site team, usually a physician or other clinician, who performs trial-related medical duties under the principal investigator's supervision.
- Superiority trialA superiority trial sets out to show that one treatment is better than another, or better than placebo.
- Surrogate endpointA surrogate endpoint is a measurement used to stand in for an outcome that matters directly to patients, such as using blood pressure in place of stroke.
- Suspected unexpected serious adverse reaction (SUSAR)A SUSAR is a serious adverse reaction whose nature or severity is not consistent with the known safety information for the product.
T
- Temperature excursionA temperature excursion is a period when investigational product was stored outside its required temperature range.
- Training recordA training record documents that a named person was trained on a specific protocol, system, or procedure on a specific date.
- Trial armAn arm is one of the groups of participants in a trial, each receiving a defined intervention.
- Trial master file (TMF)The trial master file is the complete collection of essential documents that allows the conduct of a trial and the quality of its data to be evaluated.
- Trial registrationTrial registration is publicly recording a trial's existence and design in a recognized registry before it starts enrolling.
V
- Vendor oversightVendor oversight is how a sponsor supervises the third parties it hires — CROs, central laboratories, imaging providers, technology suppliers.
- Visit windowA visit window is the permitted range of days around a scheduled visit, such as day 28 plus or minus 3 days.
- Vulnerable populationA vulnerable population is a group whose ability to give free, fully informed consent may be limited — for example children, people who cannot consent for themselves, prisoners, or people who might feel pressured by their circumstances.
W
- Warning letterA warning letter is a formal notice from the FDA stating that it has found significant regulatory violations and requiring prompt correction.
- Washout periodA washout period is time without a treatment, allowing its effects to clear before the next phase begins.
- Wearable deviceA wearable device collects health data continuously while a participant goes about normal life, such as activity, heart rate, or sleep.
- WithdrawalWithdrawal is when a participant stops taking part before completing the trial, whether by their own choice or a clinical decision.
- Work instruction (WI)A work instruction is a step-by-step document that explains how to carry out one specific task, usually sitting under a broader SOP.
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