Branching Logic
Branching logic is the set of if-then rules that route a health survey respondent, or a patient in a decision model, by earlier answers or chance events.
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.
Calibration
Calibration is the estimation of unobservable or uncertain parameters in a health economic model by adjusting them until model outputs match observed data.
Calibration of Experts
Calibration of Experts scores experts' probability judgements on seed questions with known answers, to weight their views on decision model inputs.
Causal Loop Diagram
A causal loop diagram (CLD) maps signed cause-and-effect links between variables to show the feedback loops driving a health system or decision problem.
Censoring
Censoring in survival analysis occurs when a patient's time to an event is only partly known, for example still event-free when trial follow-up ends.
Chance Node
A chance node is a point in a decision tree where an uncertain event, not a choice, decides the pathway, and its branch probabilities sum to one.
Cholesky Decomposition
Cholesky decomposition factorises a positive-definite covariance matrix into a triangular matrix and its transpose, used to sample correlated PSA inputs.
Clinical Plausibility
Clinical plausibility is the extent to which a health economic model's structure, inputs and results agree with clinical knowledge of the disease.
Closed-Form Analytical Method
A closed-form analytical method solves a health economic model with a formula, such as a matrix inverse, instead of by simulation or random sampling.
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.
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.
Compartmental Model
A compartmental model splits a population into compartments, such as susceptible, infectious and recovered, and uses equations for the flows between them.
Competing Risks
Competing risks are events that each end a patient's time at risk, such as cardiovascular and other-cause death, so the first to occur rules out the rest.
Conditional Logic
Conditional logic is the set of if-then rules in a health economic model that make risks, costs or treatment depend on age, time, history or response.
Conditional Probability
Conditional probability is the chance of an event given that another has occurred; health economic models use it for branch and transition probabilities.
Constant Hazard
Constant hazard is the survival modelling assumption that the event rate among people still at risk stays the same over time, giving exponential survival.
Constrained Optimisation
Constrained optimisation finds the choice that does best on an objective, such as QALYs gained, without breaking limits such as a fixed health budget.
Contact Rate
Contact rate is the expected number of defined, potentially transmission-relevant encounters an individual has per unit time in an infectious-disease model.