Simulated Annealing
An optimisation technique modelled on slowly cooling metal, occasionally accepting worse solutions during search to avoid becoming trapped in a poor local solution.
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.
Simulation Method
A general approach to estimating a model's results by repeatedly running it computationally, rather than solving for results using closed-form equations.
SIR Model
A basic epidemic model dividing a population into susceptible, infectious, and recovered compartments, representing flow between them using differential equations.
Skewness
A measure describing a distribution's asymmetry around its mean, positive skewness meaning a longer tail toward higher values.
Sobol Indices
Variance-based global sensitivity measures decomposing a model's total output variance into portions attributable to each input parameter and their interactions.
Sobol Sequence
A method generating a sequence of points that fills a multidimensional space more evenly than simple random sampling, improving simulation efficiency.
Social Return on Investment
A framework extending conventional return on investment analysis by monetising broader social, environmental, and health outcomes alongside financial returns.
Social Welfare Function
A mathematical representation of how individual wellbeing combines into overall social welfare, embodying explicit judgements about equality versus total welfare.
Spearman Correlation
A non-parametric measure of the monotonic relationship between two ranked variables, calculated from data ranks rather than raw values.
Spline Model
A model using piecewise polynomial functions joined smoothly at knots to represent a flexible, non-linear relationship such as time and hazard.
Standard Costing
A costing method that assigns predetermined, expected costs to services based on historical or engineered estimates rather than actual costs incurred.
Standard Deviation
A dispersion measure representing the average distance of data points from the mean, calculated as the square root of the variance.
Standard Error
A measure of an estimated parameter's precision, the standard deviation of its sampling distribution across repeated samples of the same size.
Standard Normal
A specific normal distribution with a mean of zero and standard deviation of one, used as a reference for standardising other variables.
Standardised Mortality Ratio Application
The use of a standardised mortality ratio to adjust survival estimates for background mortality within a health economic model.
Standardised Residual
A regression diagnostic dividing an observation's raw residual by its estimated standard deviation, allowing comparison on a common scale.
State Occupancy
The amount of time, typically in cycles, that a patient or cohort proportion spends within a given health state in a Markov model.
State Reward
The cost or health outcome value assigned to a health state within a Markov model, accrued for each cycle a patient occupies it.
State Space Model
A modelling framework representing a system's evolution over time through a defined set of possible states and transition probabilities between them.
State Transition Model
A general term for a decision-analytic model, such as a Markov model, representing disease progression as movement between defined health states.