Indifference Curve
An indifference curve is a curve joining combinations of two goods or health outcomes that a person values equally, showing the trade-offs they accept.
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.
Indirect Utility Assessment
Indirect utility assessment derives health state utilities by scoring patients' answers to a questionnaire such as the EQ-5D with a published value set.
Inelastic Demand
Inelastic demand is demand with a price elasticity between zero and minus one, so use falls proportionally less than price rises, as for most medical care.
Information Asymmetry
Information asymmetry occurs when a patient, insurer, doctor or other health care party knows more than another, which can distort prices and use of care.
Intangible Cost
Intangible cost is the pain, distress and lost quality of life caused by illness or treatment, which has no market price and is often measured in QALYs.
Interest Rate
An interest rate is the price of borrowing money, a yearly percentage of the loan, and a benchmark weighed in setting health appraisal discount rates.
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.
Interval Scaling
Interval scaling means equal score differences reflect equal differences in health or preference, with an arbitrary zero, so ratios of scores mean nothing.
Intervention
An intervention is any test, treatment, programme, strategy or policy aimed at health or care; HTA compares its costs and effects with alternatives.
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.
Latent Class Model
A statistical model that assumes a population consists of unobserved subgroups with distinct preferences, estimating both each subgroup's traits and individual membership probability.
Life Years Gained
Life years gained (LYG) are the extra years of mean survival an intervention gives over its comparator, without quality adjustment, in economic evaluation.
Lindahl Equilibrium
A Lindahl equilibrium is an equilibrium for a public good, such as disease surveillance, where personal prices equal marginal benefits and sum to its cost.
Liquidity Ratio
A liquidity ratio compares a health provider's cash and current assets with its short-term liabilities to show whether it can pay bills as they fall due.
Lorenz Curve
The Lorenz curve is a graph of the share of a total, such as health or health spending, held by each cumulative share of people ranked lowest to highest.
Lump-Sum Tax
A lump-sum tax is a tax whose amount no change in the taxpayer's behaviour can alter, the efficiency benchmark for funding health care from taxes.
Mapping Function
A mapping function is a fitted equation predicting a preference-based utility such as EQ-5D from clinical or other outcome scores, to estimate QALYs.
Mapping Study
Mapping study is research that estimates and validates a model predicting health state utilities from a non-preference-based measure, for use in QALYs.
Marginal Analysis
Marginal analysis compares the extra cost and extra benefit of a small change in a health service, to judge whether expanding or cutting it is worthwhile.
Marginal Cost
Marginal cost is the change in total economic cost caused by producing one additional unit of output at a specified level of activity and over a specified time horizon.