Principal Component
A principal component is an uncorrelated linear combination of centered variables whose loading vector identifies a successive direction of maximum variance in the data.
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.
Principal-Agent Problem
The principal-agent problem arises when patients or payers rely on providers who know more than they do, act unobserved and may pursue other interests.
Principal-Agent Problem in Healthcare
The specific version of the principal-agent problem in the physician-patient relationship, where clinical expertise gaps create both helpful guidance and risk of distorted recommendations.
Prior Authorization
A health plan’s advance review of a patient-specific service, medicine or item against coverage criteria before it is provided.
Prior Distribution
A prior distribution is the probability distribution for an uncertain model input, such as a treatment effect, before new data enter a Bayesian analysis.
Probabilistic Sensitivity Analysis
Probabilistic sensitivity analysis (PSA) runs a decision model many times on jointly drawn inputs to estimate expected outcomes and decision uncertainty.
Probability
Probability is a number between 0 and 1 showing how likely an event is, used in health economic models to weight costs and QALYs and express uncertainty.
Probability of Cost-Effectiveness
The probability of cost-effectiveness is the chance, given current evidence, that an intervention has the highest mean net benefit at a stated threshold.
Producer Surplus
Producer surplus is the gain suppliers of health care, such as drug makers, make by selling each unit at a price above the least they would have accepted.
Production Possibility Frontier
The production possibility frontier (PPF) shows the largest combinations of two outputs, such as health in two patient groups, that fixed resources allow.
Productive Efficiency
Productive efficiency is producing a health service or outcome at the lowest feasible cost, wasting no inputs and combining them in the least-cost mix.
Progression-Free Survival
Progression-free survival (PFS) is the time from randomisation to cancer progression or death, the trial endpoint behind the progression-free state in HTA.
PROMIS-29
PROMIS-29 is a 29-item generic health profile of seven domains plus a pain rating, used as a trial outcome and convertible to PROPr utilities for QALYs.
Propensity Score
The propensity score is a patient's probability of receiving a treatment given baseline characteristics, used to balance groups in observational studies.
Propensity Score Matching
Propensity score matching (PSM) pairs treated and untreated patients with similar propensity scores to estimate treatment effects from real-world data.
Property Graph
A property graph is a graph data model whose nodes and edges carry labels and property-value pairs, used to link health records, studies and costs.
Property Rights
Property rights are entitlements to use a resource, exclude others, take its income and transfer it, as with medicine patents or pharmacy contracts.
Proportion of Days Covered
The proportion of days covered (PDC) is the share of days in a period on which pharmacy refill records show a patient had medicine, each day counted once.
Proportional Hazards Assumption
The proportional hazards assumption is that the hazard ratio between groups, such as trial arms, is constant over follow-up while each hazard may change.
Proportional Shortfall
Proportional shortfall is the share of remaining expected QALYs that patients lose to a condition versus healthy peers, used to grade severity in HTA.