Attributable Risk
Attributable risk is the risk in exposed minus unexposed people: the excess attributed to exposure, which health economic models turn into costs and QALYs.
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.
Attrition
Attrition is the loss of participants from a trial or cohort study before follow-up ends, leaving outcome, cost and QALY data incomplete and open to bias.
Autoregressive Correlation
Autoregressive correlation is a structure for repeated measures in which correlation falls by a constant factor with each time step between measurements.
Available Case Analysis
Available case analysis is a missing data method estimating each quantity from everyone with data for it, so costs and QALYs may use different patients.
Average Treatment Effect
The average treatment effect (ATE) is the mean change in costs or health outcomes if a whole population received a treatment rather than its comparator.
Barthel Index
Barthel Index (BI) is a ten-item rating of independence in self-care and mobility, scored 0 to 100, used as an outcome in stroke and rehabilitation trials.
Basic Reproduction Number
The basic reproduction number (R0) is the average number of infections one typical case causes in a fully susceptible population, used in vaccine models.
Basket Trial
A basket trial tests one targeted treatment in several diseases, usually tumour types, that share the same biomarker, with each disease forming a basket.
Bayes Theorem
Bayes theorem is the rule that updates a prior probability with new evidence to give a posterior probability, used for diagnostic tests and model inputs.
Bayesian Adaptive Design
Bayesian adaptive design is a clinical trial design in which pre-set rules on posterior or predictive probabilities trigger changes such as early stopping.
Bayesian Analysis
Bayesian analysis updates a prior distribution with data via Bayes' theorem to give a posterior, used in HTA for evidence synthesis and decision models.
Bayesian Meta-Analysis
Bayesian meta-analysis combines prior distributions with results from several studies to give posterior and predictive distributions for an effect.
Before-and-After Study
A before-and-after study compares outcomes or costs measured before and after a health intervention or policy change, in one group or with a control group.
Begg Test
The Begg test is a rank correlation test (Kendall's tau) for small-study effects in a meta-analysis, a possible sign of publication bias.
Benefit-Risk Assessment
Benefit-risk assessment is how regulators such as the FDA and EMA judge whether a medicine's benefits outweigh its harms, given the uncertainties.
Beta Level
The predetermined acceptable probability of failing to detect a true effect, with one minus beta defining a study's statistical power.
Between-Patient Analysis
Between-patient analysis compares costs or outcomes across separate groups of patients, as in a parallel-group trial, rather than within the same patients.
Between-Study Heterogeneity
Between-study heterogeneity is variation in effects across trials in a meta-analysis beyond chance, so one pooled effect may not fit every HTA setting.
Between-Subject Variation
Between-subject variation is how much costs or outcomes differ from one patient to another, as opposed to variation in one person's repeated measurements.
Bias
Bias is systematic error that pushes a treatment effect or cost estimate in economic evaluation away from the true value; larger samples do not remove it.