Grounded Theory
Grounded theory is a qualitative research method that builds theory from data through constant comparison, theoretical sampling and coding.
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.
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.
HADS
HADS is a self-assessment scale giving separate anxiety and depression scores in physical illness, used as a non-preference-based trial outcome.
HAQ-DI
HAQ-DI is a 20-question patient-reported physical function index scored 0 to 3, used in rheumatology trials and mapped to EQ-5D in arthritis models.
Harrell C-Index
Harrell's C-index measures how well a survival model ranks patients, the share of usable pairs where the patient with the earlier event had higher risk.
Hazard Ratio
A hazard ratio (HR) is the ratio of the event rates (hazards) in two groups, the usual measure of a treatment effect on survival in trials and HTA models.
Hedges' g
Hedges' g is a standardised mean difference, the gap between two group means divided by their pooled standard deviation, corrected for small-sample bias.
Heterogeneity Assessment
Heterogeneity assessment evaluates the nature, extent, and possible causes of differences in effects or outcomes across studies, populations, or settings.
Heterogeneous Treatment Effect
A heterogeneous treatment effect is variation in a treatment's benefit or harm across patients, so the average can mislead treatment and funding decisions.
Hierarchical Model
A hierarchical model represents observations or parameters at multiple related levels and estimates variation within and between those levels.
Hierarchical Testing
Hierarchical testing controls false positives across trial endpoints by testing them in a prespecified order at full alpha, stopping at the first failure.
Hierarchy of Diagnostic Efficacy
The hierarchy of diagnostic efficacy is Fryback and Thornbury's six-level model for judging a test, from image quality and accuracy to societal value.
Historical Control
Historical control is a comparison group of past patients, from earlier trials or registries, used instead of or alongside a concurrently randomised group.
Hosmer-Lemeshow Test
The Hosmer-Lemeshow test is a goodness of fit test for logistic risk models that compares observed and predicted events in patient groups ranked by risk.
Hypothesis Testing
Hypothesis testing is a statistical method that uses study data to decide whether to reject a stated null hypothesis, such as no difference in mean cost.
I-Squared
I-squared (I2) is the percentage of variation in effect estimates across studies in a meta-analysis that is due to heterogeneity rather than chance.
Immortal Time
A period of follow-up during which, due to how exposure groups were defined, a participant could not possibly have experienced the outcome.