Skewness
A measure describing a distribution's asymmetry around its mean, positive skewness meaning a longer tail toward higher values.
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.
Slope Index of Inequality
A summary measure of absolute health inequality across a socioeconomic gradient, estimated using regression across the full distribution rather than two extremes.
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 Health Insurance
Social health insurance finances healthcare through compulsory, usually income-related contributions pooled in publicly regulated insurance funds to provide covered populations with access to care.
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.
Socioeconomic Adjustment
A modification to a risk adjustment or payment formula accounting for added costs of caring for socioeconomically disadvantaged populations.
Space Complexity
A measure of how the memory requirements of an algorithm grow as the size of the input increases.
Spearman Correlation
A non-parametric measure of the monotonic relationship between two ranked variables, calculated from data ranks rather than raw values.
Specific Stop-Loss
A reinsurance form protecting a self-insured employer against a single enrollee's claims exceeding a predefined threshold, unlike aggregate stop-loss.
Specificity
The proportion of individuals who truly do not have a condition who are correctly identified as negative by a diagnostic test.
Spline Model
A model using piecewise polynomial functions joined smoothly at knots to represent a flexible, non-linear relationship such as time and hazard.
SSI Rate
A measure of the frequency of surgical site infections following a procedure within a facility, a surgical infection prevention indicator.
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 Gamble
A health state valuation method in which respondents choose between a defined health state with certainty or a gamble between full health and death.
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
A measure comparing actual deaths observed within a population against statistically expected deaths given its risk characteristics, above one meaning worse.