Importance Sampling
A variance reduction technique for Monte Carlo simulation that deliberately oversamples important regions of a distribution, then reweights the samples to correct for this.
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.
Imputation
A technique replacing missing data values with estimated substitutes, ranging from simple mean substitution to sophisticated multiple imputation approaches.
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 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.
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.
Inflation Rate
The percentage rate at which the general level of prices for goods and services rises over a given period.
Information Asymmetry
Information asymmetry occurs when one party to an economic decision has more or better information than another, affecting choices, bargaining power and the efficiency of resulting outcomes.
Intangible Cost
A cost representing the non-financial burden of illness or treatment, such as pain or reduced quality of life, that is hard to value in money.
Integer Programming Health
An optimisation technique for resource allocation problems where decision variables must take whole-number values, such as the number of clinics to open.
Integrated Cost Analysis
A cost analysis that combines data from multiple sources, such as claims, clinical records, and patient surveys, into a single costing exercise.
Interaction Effect
The portion of output variance attributable to two or more parameters varying together, beyond what each parameter's individual effect alone would explain.
Internal Rate of Return
The discount rate at which the net present value of a stream of cash flows equals zero, used to summarise an investment's return.
Interpolation
A mathematical technique estimating an unknown value falling between two known data points, based on an assumed relationship between them.
Interquartile Range
A dispersion measure calculated as the difference between the seventy-fifth and twenty-fifth percentiles, the range containing the middle half of observations.
Interval Censoring
A form of censoring in which an event's exact time is unknown but known to fall within a specific interval, such as between visits.