Generalized Gamma Model
A survival model based on the generalised gamma distribution, nesting simpler distributions, such as the Weibull and log-normal, within one framework.
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.
Generalized Linear Model
A modelling framework extending linear regression to non-normal outcomes, such as binary or count data, via a specified link function.
Genetic Algorithm
An optimisation technique inspired by evolution that iteratively selects and combines the best candidate solutions across generations to improve results.
Geometric Mean LOS
A statistical measure of typical diagnosis-related group length of stay, using geometric rather than arithmetic mean to reduce outlier influence.
Gibbs Sampling
A Markov chain Monte Carlo algorithm generating samples from a complex joint distribution by iteratively sampling each variable from its conditional distribution.
Gini Coefficient Health
An adaptation of the Gini coefficient, originally measuring income inequality, applied to measure inequality in a health outcome, such as life expectancy.
Global Sensitivity Analysis
Sensitivity analysis techniques assessing how a model's output responds to simultaneous variation across the full range of all uncertain inputs, unlike one-way analysis.
Gompertz Distribution
A probability distribution characterised by a hazard rate rising exponentially with time, originally developed to describe human mortality increasing with age.
Gompertz Model
A survival model based on the Gompertz distribution, assuming the hazard rate rises exponentially over time, a pattern common in age-related mortality.
Goodness of Fit
A statistical measure of how well a model's predicted values correspond to observed data, used to assess whether it adequately fits the pattern.
Goodness of Fit Test
A formal statistical test determining whether observed data are consistent with a specified distribution or model, providing a basis for accepting or rejecting it.
Gradient Descent
An iterative optimisation algorithm adjusting parameters in the direction that most rapidly reduces an objective function until a minimum is reached.
Grid Search
An optimisation approach evaluating an objective function across a predefined set of candidate parameter combinations arranged in a regular grid.
Grievance Rate
A measure of how frequently patients or families file a formal grievance regarding their care, distinguished from a less formal complaint.
Group Sequential Design
A trial design incorporating planned interim analyses with predefined stopping boundaries, allowing early termination for efficacy, futility, or safety.
Group-Based Trajectory Model
A technique identifying distinct subgroups following similar patterns of change over time, without assuming everyone follows the same single trajectory.
Growth Curve Model
A modelling approach describing how an outcome changes over time within individuals, estimating both an average trajectory and individual variation around it.
Growth Mixture Model
An extension of growth curve modelling allowing unobserved subgroups to follow qualitatively different average trajectories, rather than varying only in degree.
Hale Calculation
The process of computing health-adjusted life expectancy, combining mortality data with health state prevalence and severity weights into one summary measure.
Half-Cycle Correction
An adjustment in Markov model based evaluations accounting for events occurring, on average, mid-cycle rather than precisely at its start or end.