Genetic Algorithm
A genetic algorithm is a search method based on natural selection that evolves candidate solutions, used to calibrate and optimise health economic models.
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.
Geographic Accessibility of Healthcare
Accessibility is the dimension of health care access concerned with how easily people can reach services, given location, travel time, distance and cost.
Gibbs Sampling
Gibbs sampling is a Markov chain Monte Carlo method that fits Bayesian models, such as meta-analyses, by drawing each parameter in turn given the others.
Gini Coefficient Health
The health Gini coefficient is a 0 to 1 index of how unequally a health outcome, such as length of life, is spread among people ranked by their own health.
Global Sensitivity Analysis
Global sensitivity analysis (GSA) measures how much each uncertain input of a health economic model drives variation in results as all inputs vary at once.
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
Goodness of fit describes how adequately a statistical model or probability distribution represents the observed data for its intended purpose.
Goodness of Fit Test
A goodness of fit test assesses whether a specified discrepancy between observed data and a proposed probability model is unusually large under that model’s sampling assumptions.
Gradient Descent
Gradient descent is an iterative first-order optimization method that reduces a differentiable objective function by repeatedly moving the parameter vector in the direction opposite its gradient.
Graph Database
A graph database is a database that stores data as nodes and named relationships and is queried by following them, used to link patient records to codes.
Grid Search
Grid search is an optimisation method that tests every combination of preset parameter values, used to calibrate and tune health economic models.
Grossman Model
The Grossman model is a health economics theory in which people demand health as a capital stock that depreciates with age and is built up by investment.
Grounded Theory
Grounded theory is a qualitative research method that builds theory from data through constant comparison, theoretical sampling and coding.
Group Sequential Design
A group sequential design is a randomised trial plan with interim analyses that test results against preset stopping boundaries controlling error rates.
Group-Based Trajectory Model
A group-based trajectory model (GBTM) is a finite mixture method that sorts patients into latent groups with similar paths of cost or symptoms over time.
Growth Curve Model
A growth curve model estimates how a repeatedly measured outcome changes over time, allowing the average trajectory and individual trajectories to differ under specified assumptions.
Growth Mixture Model
A growth mixture model sorts patients into latent classes whose health or cost follows a different average path over time, with variation in each class.
Habit Formation
The development of a cue-linked tendency to perform a behaviour more automatically through repetition in a recurring context.
HADS
HADS is a self-assessment scale giving separate anxiety and depression scores in physical illness, used as a non-preference-based trial outcome.