Exchangeable Correlation
A correlation structure for repeated measures assuming any two observations within the same cluster are equally correlated, regardless of their timing or order.
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.
Exploratory Factor Analysis
A technique identifying an underlying set of factors explaining correlations among observed variables, without a predetermined hypothesis, unlike confirmatory factor analysis.
F-Distribution
A continuous probability distribution arising from the ratio of two independent chi-square variables divided by their degrees of freedom, underlying analysis of variance.
Factor Analysis
A technique identifying a smaller number of underlying, unobserved factors accounting for the pattern of correlations among a larger set of measured variables.
Factor Loading
In factor analysis, a value indicating the strength of the relationship between an observed variable and an underlying latent factor.
Factor Rotation
A technique transforming an initial factor solution into a more interpretable structure, typically by maximising the contrast between high and low loadings.
Factorial Design
A trial design evaluating two or more interventions simultaneously by assigning participants to every possible combination, revealing each effect and any interaction.
Fieller Method
A technique for calculating a confidence interval around the ratio of two normally distributed variables, useful for measures such as the ICER.
Finite Mixture Model
A statistical model representing a population as a combination of a finite number of distinct subgroups, each following its own probability distribution.
Fixed Effect Model
A meta-analysis model assuming all included studies estimate the same true effect, with observed variation attributed entirely to sampling error.
Fixed Effect Synthesis
An approach to combining evidence assuming all studies estimate a single common true effect, weighting purely by statistical precision.
Fixed Effects
A panel data modelling approach estimating a separate intercept for each individual or group, controlling for all its time-invariant characteristics.
Frequentist Analysis
A statistical inference approach based on the long-run frequency properties of estimators, calculated from observed data alone, unlike a Bayesian approach.
Frequentist Meta-Analysis
An approach combining evidence using classical frequentist methods, producing a point estimate and confidence interval without formally incorporating prior beliefs.
Futility Analysis
A planned interim analysis assessing whether accumulating data suggest a trial is highly unlikely to show a significant treatment effect.
Generalized Estimating Equations
A method analysing repeated measures or clustered data, estimating population-average effects while accounting for within-cluster correlation, without a full random effects specification.
Generalized Linear Model
A modelling framework extending linear regression to non-normal outcomes, such as binary or count data, via a specified link function.
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.