Continuous Model
A continuous model is a decision model run in continuous time rather than fixed cycles, so health events can occur at any moment, governed by rates.
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 Variates
Control variates is a variance reduction method that corrects a Monte Carlo estimate, such as mean cost or QALYs, using a correlated output of known mean.
Convergence
Convergence is the point at which an MCMC run or other iterative simulation settles on a stable result as the number of iterations increases.
Correlation
Correlation is how strongly two variables move together or in opposite directions, such as costs and QALYs, without showing that one causes the other.
Correlation Matrix
A correlation matrix is a square table containing the pairwise correlation coefficients among a set of variables.
Cox Proportional Hazards
The Cox proportional hazards model is a semi-parametric survival regression that estimates hazard ratios without specifying the baseline hazard.
Cox-Snell Residual
A Cox-Snell residual is a survival model's fitted cumulative hazard at a patient's observed time, used to check overall fit against a unit exponential.
Credibility Assessment
An overall evaluation of whether a model's structure, evidence base, and validation results provide enough confidence to inform a real decision.
Cross-Validation
Cross-validation estimates how well a prediction model, such as a cost or risk model, will perform on new data by testing it on data held out from fitting.
Cumulative Hazard
Cumulative hazard, H(t), is the hazard rate summed over time in survival models. Survival equals exp(-H(t)), and unlike a probability H(t) can exceed 1.
Cure Fraction
The cure fraction is the proportion of patients a survival model expects never to die from their disease, the level at which relative survival plateaus.
Cure Fraction Model
A survival model separating a population into a cured subgroup facing only background mortality and an uncured subgroup remaining at risk of the disease event.
Cure Model
A cure model is a survival model in which disease-related excess mortality falls to zero for a share of patients, so the survival curve levels off.
Cure Rate Model
A cure rate model is a survival model that estimates the cure fraction and survival of uncured patients, used in HTA to extrapolate long-term survival.
Curve Fitting
Curve fitting is estimating a mathematical function's parameters to match observed data, as when survival curves are fitted to trial data and extrapolated.
Cycle
A cycle is a defined time interval during which a discrete-time state-transition model updates health-state occupancy and accumulates relevant outcomes and costs.
Cycle Length
Cycle length is the duration of one cycle in a Markov or other discrete-time state-transition model, such as a month or a year, set before the model runs.
Decision Node
A decision node is a point in a decision tree, drawn as a square, where the decision maker chooses between options and no probabilities are attached.
Decision Tree
A decision tree is a branching model used in economic evaluation: strategies, chance events and end points give each option's expected costs and QALYs.
Decision Tree Model
A decision tree model is an economic evaluation model whose branches map each option's patient pathways to give expected costs and QALYs per strategy.