Infection Rate
A measure of how frequently a specific type of infection occurs within a defined population and time period.
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.
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.
Informative Censoring
A form of censoring in which the reason observation ends is related to a participant's underlying risk, violating standard survival analysis assumptions.
Initial Value Problem
A differential equation together with specified starting conditions used to determine a unique solution.
Instrumental Variable
A variable associated with the exposure of interest but with no direct effect on the outcome except through that exposure, used to address confounding.
Instrumental Variable Analysis
A technique estimating a causal effect despite unmeasured confounding, using a variable that affects treatment but not the outcome except through treatment.
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.
Intention-to-Treat Analysis
A method analysing trial data by original random treatment assignment, regardless of whether participants actually received or completed that treatment.
Inter-Rater Reliability
The degree of agreement between two or more independent observers assessing the same phenomenon, commonly quantified using a statistic such as Cohen's kappa.
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.
Interim Analysis
A planned analysis of trial data conducted before final completion, typically to assess safety, efficacy, or futility and inform continuation decisions.
Interior-Point Method
An optimisation algorithm that approaches the optimum of a constrained problem by traversing the interior of the feasible region.
Internal Consistency Reliability
A measure of how well different items within an instrument, all meant to assess the same construct, produce correlated results.
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.
Interrupted Time Series
A quasi-experimental design analysing observations before and after an intervention, testing for a significant change in level or trend at that point.