Cluster Analysis
Cluster analysis is an unsupervised method that sorts patients, providers or countries into groups whose members are more alike than those in other groups.
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.
Cluster Effect
A cluster effect is the tendency of patients in the same practice or hospital to have similar outcomes and costs, so their data are not independent.
Coase Theorem
The Coase theorem holds that, with clear property rights and no transaction costs, bargaining reaches an efficient outcome whoever holds the rights.
Cognitive Bias Concept
The cognitive bias concept is systematic error in judgement, often from mental shortcuts, that skews how patients, clinicians and experts weigh evidence.
Cohen's 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.
Cohort Model
A cohort model is a health economic decision model that estimates mean costs and outcomes for a patient group as a whole, without simulating individuals.
Cohort Simulation
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 Trace
A cohort trace, or Markov trace, is the table of the share of a modelled cohort in each health state at every cycle, used to compute costs and QALYs.
Collinearity Diagnostics
Collinearity diagnostics are regression checks, such as variance inflation factors, showing when predictors overlap too much to estimate separate effects.
Common Cost Allocation
Common cost allocation is the division of a cost shared by several health services, such as overheads or a joint input, among them by a chosen rule.
Common Pool Resources
Common pool resources are goods where one user's use leaves less for others and excluding users is difficult or costly.
Common Random Numbers
Common random numbers (CRN) is a simulation method that runs competing strategies on the same random draws, so their estimated difference is less noisy.
Communality
Communality is the proportion of an observed variable's variance explained by the common factors in a factor analysis, the complement of its uniqueness.
Companion Diagnostic
A companion diagnostic (CDx) is a test that identifies patients a specific drug is likely to help or harm, so the drug and test are assessed together.
Comparability Study
A comparability study is a stepwise comparison showing a biologic is highly similar to its pre-change version or, for a biosimilar, its reference product.
Comparator
A comparator is the alternative, such as current practice or another treatment, against which a new health intervention is compared in economic evaluation.
Compartmental Model
A compartmental model splits a population into compartments, such as susceptible, infectious and recovered, and uses equations for the flows between them.
Compassionate Use
Compassionate use is the supply of an unauthorised medicine, outside a trial, to patients with a serious disease and no satisfactory authorised treatment.
Compensated Demand Curve
A compensated demand curve is a demand curve showing how much of a good, such as health care, a person would buy at each price with utility held constant.
Compensating Variation
Compensating variation (CV) is the sum that restores original utility after a health or policy change: willingness to pay for a gain or to accept a loss.