Normal Distribution
A continuous, symmetric, bell-shaped probability distribution fully described by its mean and variance, widely used to represent uncertainty in statistical applications.
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.
Null Hypothesis
In hypothesis testing, the default assumption of no true effect or difference between the groups or conditions being compared.
Numerical Integration
Techniques for approximating the value of a definite integral when an exact analytical solution is unavailable or impractical to derive.
Numerical Method
A computational technique for obtaining an approximate solution to a mathematical problem when an exact analytical solution is unavailable or impractical.
Numerical Optimisation
Computational techniques for finding the input values that minimise or maximise an objective function when no analytical solution is available.
Objective Response Rate
The proportion of patients whose tumour shrinks by a predefined amount or disappears entirely following treatment, measured using standardised radiological criteria.
Oblique Rotation
A factor analysis technique transforming a solution into a more interpretable structure while allowing the resulting factors to correlate with each other.
One-Tailed Test
A hypothesis test assessing evidence for an effect in only one specified direction, requiring strong prior justification for that direction.
One-Way Sensitivity
A sensitivity analysis in which a single input parameter is varied across a range while all others are held at their base case values.
One-Way Sensitivity Analysis
An analysis varying a single input parameter across its plausible range, one at a time, to assess its individual effect on cost-effectiveness results.
Operating Cost
The recurring cost of an organisation's ongoing operations, such as staffing, supplies, and utilities, as distinct from one-off capital investment.
Operating Margin
A financial ratio calculated as operating income divided by revenue, showing the proportion remaining after operating expenses but before non-operating items.
Opportunity Cost
The value of the next best alternative forgone when a resource is allocated to a particular use.
Opportunity Loss
The difference in value between the outcome of the optimal decision and the outcome of the decision actually made under uncertainty.
Optimal Sample Size
The sample size for a proposed study that maximises the expected net benefit of sampling, balancing information value against rising cost.
Orthogonal Design
An experimental design for a choice experiment in which attribute levels are varied independently, so each attribute's effect on preference can be separated statistically.
Orthogonal Rotation
A factor analysis technique transforming a solution into a more interpretable structure while constraining the resulting factors to remain uncorrelated.
Outlier
An observation differing markedly from other values in a dataset, either from genuine unusual variation or a measurement or entry error.
Output Maximisation
An objective in production theory of achieving the greatest possible output from a given set of inputs.
Overall Survival
A time-to-event measure defined as the time from treatment start, or trial randomisation, until death from any cause.