Structural Uncertainty
Uncertainty from the choice of a model's fundamental structure or method, such as which health states to include, unlike parameter uncertainty within a given structure.
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.
Survival Analysis
A branch of statistics concerned with the time until an event of interest occurs, appropriately accounting for censored observations.
Survival Function
A function giving the probability that a person survives without the event of interest beyond a specified point in time.
System Dynamics Model
A modelling approach representing a complex system using stocks, flows, and feedback loops to capture how it evolves through internal dynamics.
Tarone-Ware Test
A test comparing survival distributions using a weighting scheme between the log-rank and Peto tests, a compromise depending on when treatment differences emerge.
Threshold Analysis
A sensitivity analysis technique identifying the value at which an input parameter would need to be set for a model's conclusion to change.
Time Dependency
A situation where the probability of a health state transition depends on elapsed time, such as time since diagnosis, rather than staying constant.
Time-Fixed Covariate
A patient characteristic in a survival model measured once and assumed constant throughout follow-up, such as baseline age or sex.
Time-Homogeneous Model
A Markov model in which transition probabilities remain constant throughout the entire modelled time horizon, regardless of how many cycles have passed.
Time-Inhomogeneous Model
A Markov model in which transition probabilities are allowed to vary over the time horizon, such as mortality risk rising with age.
Time-to-Event
Outcome data recording the duration until a specific event of interest occurs, such as disease progression or death, possibly censored.
Time-Varying Covariate
A patient characteristic in a survival model allowed to change value over follow-up, such as a repeatedly measured biomarker.
Time-Varying Hazard
A hazard rate that changes in magnitude over follow-up, unlike a constant hazard that stays the same at every point.
Tornado Diagram
A horizontal bar chart displaying one-way sensitivity analysis results, bars ranked from largest to smallest range, resembling a tornado shape.
Total Effect Index
A variance-based sensitivity measure quantifying an input's total contribution to output variance, including its individual effect and all interactions with other inputs.
Transient State
A health state within a Markov model that a patient can leave and potentially return to, unlike an absorbing state such as death.
Transition Matrix
A table giving the probability of moving from each health state to every other state within one Markov model cycle, each row summing to one.
Transition Probability
The likelihood that a patient in a given health state at a cycle's start will move to another state, or stay, by its end.
Transition Reward
A cost or outcome value applied at the moment a patient moves between two health states, unlike a state reward accrued over time.
Transmission Model
A model explicitly representing how an infectious disease spreads through a population by tracking interaction between infectious and susceptible individuals.