Continuous Data
Continuous data are outcomes measured on a numerical scale that can take any value within a range, such as blood pressure, cost or utility.
Encyclopaedia
Explore comprehensive, evidence-informed explanations of key health economics concepts, including their development, application and relationships to other concepts. Published entries are validated through human expert review.
Concepts, entries and ontology terms
A concept page is a published entry on the wiki. Some concepts also have a full encyclopaedia article. The Health Economics Ontology (HEO) holds every concept, including dictionary terms without an article, so it is larger than the list of published pages. The knowledge graph shows how concepts relate to each other.
Control Arm
A control arm is the trial group given placebo, no treatment, another dose or another treatment, against which outcomes on the new treatment are compared.
Convergent Validity
Convergent validity is evidence that a health measure correlates, as predicted in advance, with other measures of the same or a closely related construct.
Cook's Distance
Cook's distance is a regression diagnostic measuring how much all fitted values change when one observation, such as one patient's cost record, is removed.
Copas Model
The Copas model is a selection model for publication bias in meta-analysis that re-estimates the pooled effect under assumed rates of non-publication.
COPD Assessment Test
COPD Assessment Test (CAT) is an eight-item patient questionnaire, scored 0 to 40, on how COPD affects health status, used in trials and GOLD assessment.
Core Outcome Set
Core outcome set (COS) is the agreed minimum set of outcomes all trials in a condition should measure and report, so results can be compared and combined.
Core Outcome Set Development
Core outcome set development is the consensus study, usually a review, Delphi and meeting, agreeing what trials in a condition should measure and report.
Correlation Coefficient
A correlation coefficient is a statistic from -1 to +1 giving the direction and strength of association between paired variables, such as costs and QALYs.
Coverage Error
Coverage error arises when the sampling frame of a health survey or register misses part of the target population or includes people outside it.
Credible Interval
A credible interval is a Bayesian range that contains an unknown parameter, such as a treatment effect, with a stated posterior probability, often 95%.
Credible Interval Estimation
The Bayesian process of calculating a range of plausible values for a parameter based on its estimated posterior probability distribution.
Criterion Validity
Criterion validity is the degree to which a measure's scores agree with a gold standard for the same concept, assessed at the same time or later.
Critical Appraisal
Critical appraisal is the structured judgement of whether a study, model or economic evaluation is sound and relevant enough to inform a health decision.
Critical Value
A critical value is a cutoff on a test statistic's reference distribution that defines a rejection boundary for a specified hypothesis test and error level.
Cross-Cultural Validity
Cross-cultural validity is how far items in a translated or culturally adapted health questionnaire, such as the EQ-5D, perform like the original version.
Cross-Sectional Design
A cross-sectional design is an observational design that measures exposure and outcome in a population at one point in time, often to estimate prevalence.
Crossover Design
Crossover design is a clinical trial design in which each participant receives two or more treatments in a randomised order and acts as their own control.
Crossover Trial
A trial in which participants sequentially receive two or more treatments under comparison, with each participant's response compared against their own.
Cumulative Incidence
Cumulative incidence, or risk, is the proportion of people free of an event at the start of a period who have it by the end, such as a 5-year stroke risk.