Dictionary

C

Cluster EffectTermClustering Effect, Intracluster Correlation

The tendency for individuals within the same naturally occurring group, such as a hospital, to have more similar outcomes than those in other groups.

Cluster RandomizationConceptCluster Randomisation, Group Randomisation

Cluster randomization assigns intact groups, rather than individual participants, to study strategies and requires design and analysis that account for similarities among members of each group.

Co-Primary OutcomeTermCo-Primary Endpoint, Coprimary Outcome

One of two or more outcomes jointly designated as primary in a trial, with success possibly requiring a significant effect on all of them.

Coase TheoremConceptCoase's Theorem, Coasean Bargaining

The Coase theorem holds that, with clear property rights and no transaction costs, bargaining reaches an efficient outcome whoever holds the rights.

COBRA CoverageTermCOBRA, Continuation Coverage

A US federal provision letting individuals temporarily continue their employer-sponsored insurance after job loss, typically by paying the full premium themselves.

CochraneTermSystematic Review Organisation, Evidence Review Body

An international organisation producing systematic reviews of healthcare interventions to a standardised, rigorous methodology, widely regarded as a leading evidence source.

Code of ConductTermConduct Code, Ethics Code

A formal document outlining an organisation's expected ethical standards and behavioural expectations, typically covering conflicts of interest and billing integrity.

Code StatusTermResuscitation Status, DNR Status

A documented designation specifying which resuscitation and life-sustaining interventions should be attempted in the event of cardiac or respiratory arrest.

Coding AccuracyTermCoding Correctness, Code-Assignment Accuracy

The degree to which diagnosis and procedure codes assigned to a patient encounter correctly reflect the clinical care actually documented.

Coding ComplianceTermCoding Adherence, Billing Compliance

Adherence to established coding rules when assigning diagnosis and procedure codes for billing, preventing both underbilling and improper overbilling.

Coding ErrorTermMiscoding, Code Assignment Error

A mistake introduced when categorical data, such as diagnosis codes, are incorrectly assigned during data processing, potentially misclassifying patients or events.

Coeliac Disease EconomicsTermCeliac Disease Economics, Gluten Enteropathy Economics

The application of health economic evaluation to coeliac disease, an autoimmune condition triggered by gluten, covering diagnosis and lifelong gluten-free diet cost.

CoercionTermUndue Pressure, Compelled Participation

The use of an explicit or implicit threat to compel an individual to participate in research against their genuine free will.

Cognitive Bias ConceptConceptCognitive Bias, Judgement Bias

A systematic deviation from rational judgement caused by the mental shortcuts people use to process information.

Cognitive DeclineTermCognitive Impairment, Mental Decline

A reduction in mental abilities, including memory, attention, and problem-solving, ranging from normal ageing to severe impairment such as dementia.

Cognitive FunctionTermCognition, Mental Function

A clinical outcome domain capturing mental processes, including memory, attention, and executive function, commonly measured using standardised neuropsychological tools.

Cognitive FunctioningTermCognitive Capacity, Cognitive Ability

A clinical outcome domain describing mental capacities, including memory, concentration, and problem-solving, typically assessed using standardised tests or questionnaires.

Cognitive ResponseTermCognitive Improvement Response, Neurocognitive Response

A biomarker or clinical endpoint indicating a measurable change in cognitive test performance following treatment, used to assess mental function effect.

Cognitively Impaired ResearchTermResearch with Impaired Capacity, Diminished-Capacity Research

Research involving participants whose cognitive capacity may limit their ability to provide fully informed consent, requiring additional ethical safeguards.

Cohen's dConceptCohen d

Cohen's d is a standardised effect size: the difference between two group means divided by their pooled standard deviation, used to compare studies.

CoherenceTermProbabilistic Consistency, Axiom Consistency

A property requiring a set of subjective probability judgements to satisfy the basic axioms of probability theory, such as summing to one.

Cohort DesignConceptCohort Study Design, Prospective Design

A cohort design follows a defined group of people from an established starting point to observe subsequent outcomes and, when relevant, compare those outcomes across baseline exposures or treatment strategies.

Cohort ModelConceptCohort-Level Model, Markov Cohort Approach

A cohort model follows the expected movement of a defined group through mutually exclusive health states over time.

Cohort SimulationConceptCohort-Level Simulation, Markov Cohort Run

Cohort simulation runs a Markov or other state-transition model by moving the expected shares of a hypothetical cohort between health states each cycle.

Cohort StudyTermLongitudinal Study, Prospective Study

An observational study following a group sharing a common exposure or characteristic forward in time to observe subsequent health outcomes.

Cohort TraceConceptMarkov Trace, State-Occupancy Trace

A cohort trace is the cycle-by-cycle record of a state-transition model’s expected cohort distribution across its health states under a specified strategy.

CoinsuranceConceptCo-insurance, Percentage Cost-Sharing

Coinsurance is the percentage of the allowed cost of a covered healthcare service that an insured person pays under the plan's cost-sharing rules, commonly after satisfying the applicable deductible.

Coinsurance MaximumTermCoinsurance Cap, Coinsurance Limit

The highest total amount an insured person will pay in coinsurance within a defined period, beyond which the insurer covers everything further.

Coinsurance RateConceptCoinsurance Percentage, Cost-Share Rate

The specific percentage of a covered service's cost an insured person is responsible for paying under a coinsurance arrangement.

Collaborative CareTermIntegrated Behavioural Care, Care Manager Model

A structured model, well established for depression management, in which a primary care provider works with a care manager and specialist to adjust treatment.

Collinearity DiagnosticsTermMulticollinearity Diagnostics, VIF Analysis

Statistical techniques detecting when two or more predictor variables in a regression model are highly correlated, hindering reliable individual effect estimates.

Colorectal Cancer ScreeningTermCRC Screening, Colonoscopy Screening

A public health strategy using colonoscopy or stool-based testing to detect colorectal cancer or precancerous polyps in asymptomatic individuals.

Colorectal EconomicsTermColorectal Disease Economics, Bowel Economics

The application of health economic evaluation to conditions affecting the colon and rectum, spanning cancer screening, inflammatory bowel disease, and diverticular disease.

Combination PricingTermCombo Pricing, Regimen Pricing

A pricing approach applied when two or more treatments are used together, requiring negotiation to establish a total price for the combined regimen.

Combination TherapyTermCombination Treatment, Multi-Drug Therapy

A treatment approach using two or more distinct agents together, often to achieve a greater effect than either alone or address multiple mechanisms.

Comfort CareTermSymptom-Focused Care, End-of-Life Symptom Relief

A treatment approach focused entirely on relieving symptoms and maximising quality of life, without pursuing curative or life-prolonging treatment.

Comfort Measures OnlyTermCMO, Symptom-Relief Care

A clinical designation indicating care should focus exclusively on comfort and symptom relief, with other interventions, including resuscitation, withheld.

Commercial Access AgreementTermCommercial Arrangement, Payer Access Deal

A negotiated arrangement between a manufacturer and payer establishing the price and conditions, sometimes outcomes-based, under which a treatment is made available.

Commercial PayerTermCommercial Insurer, Private Health Insurer

A private insurance company providing coverage funded through premiums paid by employers or individuals, unlike a public payer such as a government programme.

Commitment InterventionTermCommitment Device, Self-Binding Mechanism

A mechanism allowing individuals to voluntarily restrict their own future choices in advance, such as committing to a savings plan.

Committee DiscussionTermCommittee Deliberation, Appraisal Discussion

The deliberative process during which appraisal committee members review and debate submitted evidence before reaching a final recommendation.

Common Cause VariationTermRandom Variation, Inherent Variation

Variation resulting from normal, inherent randomness within a stable system, unlike special cause variation from a specific, identifiable factor.

Common ComparatorTermShared Comparator, Common Reference Treatment

A treatment directly compared against two or more other treatments in separate trials, providing the link needed for an indirect comparison.

Common Cost AllocationTermJoint Cost Allocation, Shared Cost Allocation

The process of assigning a cost jointly incurred across multiple services or departments to each of them using a chosen allocation rule.

Common Pool ResourcesTermCommon-Pool Goods, Commons

Resources that are non-excludable but rivalrous, so access cannot easily be restricted while use by one party reduces availability for others.

Common Random NumbersConceptCRN, Correlated Sampling

Common random numbers is a simulation variance-reduction method that uses corresponding random input streams across alternative strategies to improve the precision of their estimated difference when paired outputs are positively correlated.

Common Terminology CriteriaTermCTCAE, Adverse Event Grading

A standardised grading system classifying the severity of adverse events observed in trials, widely used across oncology and other areas.

CommunalityConceptCommon Variance, Shared Variance Proportion

Communality is the portion of an observed variable's variance attributed to the common factors retained in a factor-analysis model.

Communication HTA TeamTermHTA Communications Team, Dissemination Team

A functional group within an assessment organisation responsible for translating and disseminating technical findings to clinicians, patients, and the public.

Communication OpennessTermOpen Communication, Speaking Up Climate

A patient safety culture dimension measuring how comfortable staff feel speaking up about safety concerns without fear of repercussion.