Transmission Probability
The likelihood that an infectious disease passes from an infected to a susceptible individual during a single contact between them.
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.
Trapezoidal Rule
A numerical integration technique approximating a definite integral by dividing the area under a curve into trapezoids and summing their areas.
Treatment Effect
The change in an outcome attributable to a specific treatment, distinguished from changes that would have occurred regardless due to other factors.
Treatment Effect Heterogeneity
Variation in the size or direction of a treatment's effect across different patients, so a trial's average effect may not fit any one person.
Trend Analysis
A statistical technique examining patterns of change in a variable over successive time periods, distinguishing direction from short-term fluctuation.
Truncation
A situation in survival or longitudinal analysis where certain observations are systematically excluded based on a variable's value, such as required registration.
Truncation Error
The error introduced by approximating a mathematical process using a finite number of terms or steps.
Tunnel State
A modelling technique creating temporary, time-specific states a patient passes through in sequence, letting a Markov model approximate time-dependent risk.
Two-Stage Meta-Analysis
An individual patient data meta-analysis first analysing each study separately, then combining the resulting study-level estimates using standard methods.
Two-Tailed Test
A hypothesis test assessing evidence for an effect in either direction, without specifying in advance whether it is expected to be better or worse.
Two-Way Sensitivity Analysis
An analysis varying two parameters together across a grid of combinations, typically shown as a contour plot or heat map of results.
Type I Error
In hypothesis testing, the error of incorrectly rejecting a true null hypothesis, concluding a genuine effect exists when it does not.
Type II Error
In hypothesis testing, the error of failing to reject a false null hypothesis, concluding no effect exists when a genuine effect is present.
Unbiasedness
A property of an estimator whose expected value, across repeated samples, equals the true underlying value of the parameter being estimated.
Uncertainty Quantification
The formal process of measuring how much confidence should be placed in a model's results, given the sources of uncertainty affecting it.
Uniform Distribution
A probability distribution in which every value within a defined range is equally likely to occur.
Unimodal Hazard
A hazard function that rises to a single peak and then declines over follow-up, rather than a monotonic or bathtub pattern.
Universal Health Coverage
Universal health coverage is the goal that everyone can obtain the quality health services they need throughout life without experiencing financial hardship.
Unstructured Correlation
A correlation structure for repeated measures allowing the correlation between every pair of time points to be estimated freely and independently.
Utilisation Rate
A measure of how frequently a service or resource is used within a population, typically expressed relative to population size.