Visual Analogue Scale
A health state valuation method in which respondents mark a perceived health state on a continuous line anchored between worst and best imaginable health.
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.
VOI Analysis
An abbreviation for value of information analysis, applying formal decision-theoretic methods to quantify the expected benefit of reducing decision uncertainty.
Wald Test
A statistical test assessing whether an estimated parameter differs significantly from a specified value, based on the ratio of estimate to standard error.
Weak Dominance
A situation where an intervention is inferior not to any single alternative but to a combination of two other available options.
Weibull Distribution
A flexible probability distribution capable of a monotonically increasing or decreasing hazard rate depending on its shape parameter.
Weibull Model
A survival model based on the Weibull distribution, representing an increasing or decreasing hazard over time, though restricted to a monotonic pattern.
Weighted Log-Rank
A class of tests comparing survival distributions using different weights at different follow-up times, including the log-rank, Peto, and Tarone-Ware tests.
Wilcoxon Test
A test comparing survival distributions that gives greater weight to earlier event times than later ones, unlike the standard log-rank test.
Willingness to Accept
The minimum compensation an individual would require to voluntarily give up a good or accept a worse outcome.
Willingness to Pay
The maximum amount of money an individual would give up to obtain a good or avoid a negative outcome.
Willingness-to-Pay Estimation
The empirical process of measuring willingness to pay, typically through stated preference methods such as contingent valuation or discrete choice experiments.
Willingness-to-Pay Threshold
The maximum amount a decision-maker is prepared to pay for an additional unit of health benefit, used to judge acceptable value for money.
Within Subject Variation
The degree to which repeated measurements on the same individual fluctuate over time, unlike between-subject variation reflecting differences across individuals.
Working Correlation
In generalised estimating equations, an assumed correlation structure among repeated observations, improving statistical efficiency even if not perfectly correct.
Years Lived with Disability
A component of the disability-adjusted life year representing healthy years lost to a non-fatal condition, found by multiplying its prevalence by its disability weight.
Years of Life Lost
A premature mortality measure calculated as the difference between age at death and a reference life expectancy, summed across deaths from a cause.
Yld Calculation
The process of computing years lived with disability by multiplying the prevalent cases of a condition by its average duration and disability weight.
Yll Calculation
The process of computing years of life lost by summing, across all deaths from a cause, the gap between age at death and standard life expectancy.
Z-Score
A standardised statistic representing how many standard deviations an observation lies above or below the mean of its distribution.