Performance Bias
Performance bias is systematic error from differences in care, co-interventions or behaviour between trial arms, often because people know the allocation.
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.
Period Prevalence
Period prevalence is the share of a population with a condition at any time in a set interval, such as a year, used to count cases in annual costings.
PHQ-9
PHQ-9 is a nine-item patient-reported depression severity measure scored 0 to 27, used as a trial outcome and mapped to EQ-5D utilities for QALYs.
Point Prevalence
Point prevalence is the share of a population with a condition on one date, counting new and existing cases, used to size caseloads and model cohorts.
Poisson Distribution
The Poisson distribution is a probability model for counts of events, such as hospital admissions, that occur independently at a constant rate over time.
Poisson Regression
Poisson regression models counts of health care events, such as admissions, as rates that change multiplicatively with patient and treatment factors.
Population Attributable Fraction
The population attributable fraction (PAF) is the share of a population's disease cases or burden that would not occur if a causal exposure were removed.
Positive Likelihood Ratio
The positive likelihood ratio (LR+) is sensitivity over (1 minus specificity), the factor by which a positive result multiplies disease odds in HTA models.
Positive Predictive Value
Positive predictive value (PPV) is the share of people with a positive test result who truly have the condition, which models use to count false positives.
Post-Test Probability
Post-test probability is the chance of a condition after a test result, updated from pre-test probability by its likelihood ratio, in diagnostic models.
Posterior Distribution
The posterior distribution is the probability distribution of an uncertain model input, such as a treatment effect, after a prior is updated with new data.
Pre-Test Probability
Pre-test probability is the chance a patient has the condition before testing, judged from presenting features, and it shapes test cost-effectiveness.
Prevalence
Prevalence is the proportion of a population living with a condition at a given time or over a period, used to size patient groups and annual costs.
Prevalence Ratio
The prevalence ratio (PR) is the prevalence of a condition in an exposed group divided by that in an unexposed group, used to compare disease burden.
Primary Research
Primary research is research that collects new data, as in trials, cohort studies and preference or costing surveys, rather than reusing existing data.
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.
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.
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.