Imputation
A technique replacing missing data values with estimated substitutes, ranging from simple mean substitution to sophisticated multiple imputation approaches.
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.
Incidence
The number of new cases of a disease occurring within a defined population over a specified period, unlike prevalence, which counts existing cases.
Incidence Rate
A measure of disease frequency calculated as new cases divided by total person-time at risk observed, accounting for varying follow-up lengths.
Incidence Rate Ratio
A measure comparing the incidence rate of an outcome between two groups, accounting for differences in total person-time at risk.
Income Elasticity of Demand
A measure of how quantity demanded responds to a change in consumer income, calculated as percentage change in demand over percentage change in income.
Incremental Cost
Incremental cost is the difference in expected total cost between one healthcare option and its stated comparator, calculated using the same population, perspective, time horizon, currency, price year and costing methods.
Incremental Cost-Effectiveness Ratio (ICER)
The incremental cost-effectiveness ratio, or ICER, is incremental cost divided by incremental effectiveness, expressing the additional cost per additional unit of outcome when ratio interpretation is meaningful.
Incremental Cost-Utility Ratio
The difference in cost between two interventions divided by the difference in quality-adjusted life years they produce.
Incremental Effectiveness
Incremental effectiveness is the difference in health outcomes between an intervention and its comparator, calculated in a consistent outcome unit and comparison direction.
Incremental Net Benefit
The difference in expected net benefit between two competing interventions, found by converting the incremental health effect into money and subtracting incremental cost.
Incremental Net Monetary Benefit
Incremental net monetary benefit, or INMB, converts the difference in health outcomes between two alternatives into a monetary value at a stated cost-effectiveness threshold and then subtracts their difference in cost.
Independent Censoring
A form of censoring in which the reason observation ends is unrelated to a participant's underlying risk, satisfying standard survival analysis assumptions.
Indirect Comparison
A method estimating the relative effect of two treatments never studied against each other directly, using their separate effects versus a shared comparator.
Indirect Elicitation
A health state valuation approach in which a descriptive questionnaire's responses are converted into a utility value using a pre-existing scoring algorithm.
Indirect Treatment Comparison
A method estimating the relative effect of two treatments never directly compared, typically via a common comparator both have been separately tested against.
Indirect Utility Assessment
The process of obtaining a health state utility value by applying a scoring algorithm from a prior valuation study to a respondent's questionnaire answers.
Individual Patient Data Meta-Analysis
A meta-analysis obtaining and analysing original patient-level data from each study, rather than relying only on published summary results.
Individual Patient Meta-Analysis
An evidence synthesis approach combining original patient-level records from multiple studies into one unified dataset, rather than only summary statistics.
Individual Patient Simulation
A modelling technique simulating a large number of individual patients one at a time, each following their own pathway from random sampling.
Inelastic Demand
A condition in which quantity demanded changes proportionally less than a given price change, indicating consumers are relatively insensitive to price.