Interpersonal Comparison of Utility
An interpersonal comparison of utility is a value judgement comparing the welfare levels or gains of different people, as summing QALYs or pounds does.
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.
Interpolation
Interpolation estimates a value between observed or modelled data points using an assumed relationship across the interval.
Interquartile Range
The interquartile range (IQR) is the gap between the 25th and 75th percentiles, the spread of the middle half of data such as skewed patient costs.
Interval Censoring
Interval censoring occurs when a patient's event time, such as disease progression, is known only to lie between two assessments, such as two trial scans.
Intervention
An intervention is any test, treatment, programme, strategy or policy aimed at health or care; HTA compares its costs and effects with alternatives.
Intraclass Correlation
The intraclass correlation (ICC) is the share of variance in a health outcome lying between patients or clusters, used to judge reliability and clustering.
Jackknife
The jackknife is a resampling method that recomputes an estimate, such as mean cost, leaving out each observation in turn to gauge bias and standard error.
Joint Model
A joint model fits a repeatedly measured biomarker and time to an event such as death together, so survival estimates for economic models reflect the link.
K-Fold Cross-Validation
An internal validation procedure that repeatedly fits a model on all but one of K data folds and evaluates it on the held-out fold.
Kakwani Index
The Kakwani index measures the progressivity of health care financing as the concentration index of payments minus the Gini coefficient of ability to pay.
Kalman Filter
A recursive estimator that predicts an evolving latent state and updates that estimate and its uncertainty when a new noisy measurement arrives.
Kaplan-Meier Curve
A graphical display of the Kaplan-Meier survival estimate, shown as a step function that decreases at each observed event over time.
Kaplan-Meier Estimator
The Kaplan–Meier estimator calculates a non-parametric estimate of the survival function when follow-up can be right-censored.
Kaplan-Meier Method
The overall approach of estimating and comparing survival functions using the Kaplan-Meier estimator, accounting for censored observations in time-to-event data.
Kappa Statistic
The kappa statistic (Cohen's kappa) measures chance-corrected agreement between two raters on a categorical judgement, such as reviewers screening studies.
Kendall Tau
Kendall tau is a rank correlation from minus one to one, comparing how often two rankings of health states or treatments order pairs alike or reversed.
Kurtosis
Kurtosis is the standardised fourth moment of a distribution, a measure of tail heaviness that flags rare extreme values such as very high patient costs.
Landmark Analysis
Landmark analysis is a survival method that starts follow-up at a set time, keeps only patients still event-free then and groups them by their status then.
Last Observation Carried Forward
Last observation carried forward (LOCF) fills missing trial follow-up values with each participant's last observed value, assuming no change after dropout.
Latent Class Analysis
Latent class analysis (LCA) finds unobserved patient subgroups from patterns in categorical data, such as recorded conditions or diagnostic test results.