Nominal Scale
Nominal scale is a level of measurement whose numbers only name categories, such as trial arm or EQ-5D dimension, so counts are valid but averages are not.
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.
Non-Inferiority Trial
A non-inferiority trial tests whether a new treatment is worse than an active comparator by less than a preset margin, often because it costs less.
Non-Mixture Cure Model
A non-mixture cure model is a survival model used in HTA whose survival curve levels off at the cure fraction without splitting patients into two groups.
Non-Parametric Estimation
Non-parametric estimation derives a survival curve or other distribution from observed data, as Kaplan-Meier does, with no assumed mathematical form.
Non-Parametric Survival
Non-parametric survival is a survival estimate taken directly from observed time-to-event data, such as a Kaplan-Meier curve, with no assumed distribution.
Non-Randomised Controlled Trial
A non-randomised controlled trial is a trial where investigators assign people to treatment or control without chance, so its estimates risk confounding.
Nonlinear Programming
Nonlinear programming is the optimization of an objective function subject to equality, inequality, or bound constraints when the objective or at least one constraint is nonlinear in the decision variables.
Normal Distribution
The normal distribution is a symmetric bell-shaped curve set by a mean and standard deviation, used in health economics for estimated means and log ratios.
Normative Economics
Normative economics is the branch of economics that ranks policies by stated criteria of what ought to be, such as maximising health from an NHS budget.
Nottingham Health Profile
Nottingham Health Profile (NHP) is a generic measure of perceived physical, social and emotional health problems, scored by section, not as a QALY utility.
Null Hypothesis
The null hypothesis (H0) is the claim a significance test assesses data against, usually of zero effect, such as no difference in mean cost or QALYs.
Number Needed to Treat
The number needed to treat (NNT) is how many patients must be treated to prevent one more adverse event, equal to 1 divided by the absolute risk reduction.
Numerical Integration
Numerical integration approximates the area represented by a definite integral when an exact antiderivative is unavailable, inconvenient or evaluated from discrete data.
Numerical Method
A numerical method is a systematic computational procedure that approximates the solution of a mathematical problem through finite arithmetic operations, with accuracy assessed through error, convergence, stability, and conditioning.
Numerical Optimisation
Numerical optimisation uses iterative computational methods to find decision or parameter values that minimise or maximise an objective function.
NYHA Functional Classification
NYHA Functional Classification is a clinician-rated four-class grading of heart failure, used to set eligibility, health states and utilities in models.
Objective Response Rate
Objective response rate (ORR) is the proportion of cancer trial patients with a complete or partial tumour response, an early efficacy measure in HTA.
Oblique Rotation
Oblique rotation is a factor analysis step that lets rotated factors correlate, used when health domains such as physical and mental health are related.
Observational Study
A study that observes exposures and outcomes without investigator assignment of the exposure under investigation, using a specified design to describe patterns or assess associations and, under additional assumptions, causal effects.
Observed-to-Expected Ratio
The observed-to-expected (O/E) ratio divides a provider's observed events, such as deaths, by the number expected for its case mix, so 1 means as expected.