Restricted Mean Survival Time
A survival summary measure calculated as the area under the survival curve up to a specified time point, an alternative to the hazard ratio.
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.
Retrospective Risk Adjustment
A risk adjustment method calculating payment adjustments after a coverage period ends, based on actual observed diagnoses and costs.
Return on Assets
A financial ratio calculated as net income divided by total assets, showing how efficiently an organisation uses its assets to generate profit.
Return on Equity
A financial ratio calculated as net income divided by owner equity, showing the return generated on capital invested by an organisation's owners.
Return on Investment
A measure of an investment's profitability, calculated as the net gain from the investment divided by its cost.
Reynolds-Smolensky
An index measuring the redistributive effect of a tax or transfer system, calculated as the difference between pre-tax and post-tax income Gini coefficients.
Right Censoring
The most common form of censoring, occurring when follow-up ends or a patient is lost before the event of interest has occurred.
Risk Adjustment
A methodology adjusting payments to insurers or providers based on the health status and expected costliness of the population they cover.
Risk Corridor
A risk-sharing mechanism where government shares in an insurer's unexpectedly high losses or profits relative to a projected target, stabilising a new market.
Risk Difference
The absolute difference between the risk of an outcome in one group and in another, the excess or reduced risk from an exposure.
Risk Pooling
Risk pooling is the health-financing process of combining prepaid funds so that the costs of healthcare are shared across members rather than borne entirely by individuals when they become ill.
Risk Ratio
A measure calculated as the ratio of risk in one group compared to another, synonymous with relative risk for event comparisons.
Risk Score
A numerical value representing an individual's predicted relative healthcare cost, calculated using a risk adjustment model.
Robust Optimisation
An optimisation approach seeking a solution that performs well across a range of possible uncertain parameter values, rather than one best-guess scenario.
Robust Standard Error
An estimate of a regression coefficient's statistical uncertainty that remains valid even when standard modelling assumptions, such as constant error variance, are violated.
ROC Curve
A graph depicting the trade-off between a test's true positive rate and false positive rate across a full range of decision thresholds.
Rollback
An alternative term for folding back, the process of solving a decision tree by working backward from final outcomes to the initial node.
Root Mean Square Error
A measure of average prediction error, the square root of the average squared difference between predicted and observed values, in the outcome's units.
Rounding Error
The difference introduced when a numerical value is rounded to fit a limited number of digits.
Royston-Parmar Model
A class of flexible parametric survival models using restricted cubic splines to represent a transformed survival or hazard function while remaining fully parametric.