Stochastic Programming
Stochastic programming is optimisation that includes parameter uncertainty, used in health care to choose a vaccination policy before outcomes are known.
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.
Stock and Flow Model
A stock and flow model tracks health quantities, such as people with a disease, as stocks that change over time only through inflow and outflow rates.
Structural Uncertainty
Structural uncertainty is doubt about how a health economic model represents a decision problem, such as its health states, pathways or extrapolation.
Subgroup Analysis
Subgroup analysis estimates treatment effects, costs or cost-effectiveness separately for defined groups of patients to test whether they differ.
Survival Analysis
Survival analysis is the statistical study of time to an event such as death when follow-up is incomplete, giving survival curves for economic models.
Survival Function
The survival function, S(t), is the probability that a patient stays alive or free of a defined event beyond time t, used to model life years and QALYs.
System Dynamics Model
A system dynamics model simulates a health system in aggregate as stocks, flows and feedback loops, projecting how policies play out over time.
Tarone-Ware Test
The Tarone-Ware test is a weighted log-rank test comparing survival between trial arms, weighting each event time by the square root of the number at risk.
Threshold Analysis
Threshold analysis finds the switching value, the level an uncertain input must reach for the preferred option in a health economic model to change.
Time Dependency
The property of a risk, effect, cost, utility or other model input changing according to a specified time scale, such as attained age or time since an event.
Time-Homogeneous Model
A time-homogeneous model is a Markov model whose transition probabilities are the same in every cycle, so health state risks never change with age or time.
Time-Inhomogeneous Model
A time-inhomogeneous model is a Markov model whose transition probabilities can change between cycles, so a risk such as death can rise as the cohort ages.
Time-to-Event
Time-to-event data record the time until an event such as death or progression, with some times censored, and supply survival inputs to economic models.
Time-Varying Covariate
A time-varying covariate is a predictor in a survival model, such as drug use or a biomarker level, whose value is updated during follow-up.
Time-Varying Hazard
A time-varying hazard is an event rate among people still at risk that rises, falls or turns over follow-up, as in many health economic survival models.
Tornado Diagram
A tornado diagram is a bar chart of one-way sensitivity results in a cost-effectiveness model, ranking inputs so the widest swing in the result is on top.
Total Effect Index
The total effect index is the share of a health economic model output's variance due to one uncertain input, counting its main effect and all interactions.
Transient State
A transient state is a health state in a Markov model that patients eventually leave for good, possibly after several stays, unlike an absorbing state.
Transition Matrix
A transition matrix is the table of probabilities of moving between, or staying in, health states in one cycle of a Markov model, with rows summing to one.
Transition Probability
A transition probability is the chance of moving from one health state to another, or staying, during one cycle of a Markov or state-transition model.