Concept Architecture
Concept
Theoretically, Preference Weight is a numerical value that quantifies the relative desirability of a health state, attribute level or health outcome based on individual or societal preferences. It is founded on utility theory and preference measurement and represents the contribution of a specific health state or attribute to an overall utility value. Preference weights exist to convert descriptive health states into quantitative utility values suitable for economic evaluation.
Mathematically, preference weights have no universally recognised canonical mathematical formula. They are estimated from preference elicitation studies using recognised valuation methods and are incorporated into utility functions or scoring algorithms to calculate overall health state utility. The mathematical framework combines estimated weights with health state descriptions to derive preference-based utility values.
In practice, preference weights are estimated using methods such as standard gamble, time trade-off, discrete choice experiments and paired comparison. Country-specific value sets are developed by applying statistical models to preference data collected from representative populations. These published preference weights are subsequently used to score instruments such as EQ-5D, HUI, SF-6D and AQoL for quality-adjusted life year estimation and health technology assessment.
Purpose
Used to quantify the relative value assigned to health states or health state attributes, enabling calculation of preference-based utility values for quality-adjusted life year estimation and economic evaluation.
Mathematical Formulae
Primary Formula
There is no universally recognised canonical mathematical formula.
Supporting Formulae
For an additive utility model:
U = ????� w?x?
where:
- U = overall utility
- w? = preference weight for attribute i
- x? = observed level or utility contribution of attribute i
Related Mathematical Methods
- Utility function estimation
- Multi-attribute utility theory
- Standard gamble
- Time trade-off
- Discrete choice experiments
- Conditional logit modelling
- Maximum likelihood estimation
Example
An EQ-5D value set assigns a preference weight of ?0.214 to severe pain/discomfort and ?0.069 to moderate mobility problems. These preference weights are combined with the remaining attribute weights and the model intercept to calculate the overall utility value for the reported health state.
Excel Implementation
| Function | Example Formula | Health Economics Application |
|---|---|---|
| SUMPRODUCT | =SUMPRODUCT(B2:F2,$B$1:$F$1) | Combines preference weights with health state attribute values to calculate utility. |
| XLOOKUP | =XLOOKUP(A2,Weights[Level],Weights[Weight]) | Retrieves published preference weights from a value set. |
| INDEX | =INDEX(Weights[Weight],MATCH(A2,Weights[Level],0)) | Returns the appropriate preference weight for a health state level. |
| SUM | =SUM(B2:F2) | Aggregates weighted attribute contributions during utility calculation. |
VBA (Optional)
Automate the application of published preference weights to questionnaire responses to generate utility values for economic evaluation.
Sources
- Brazier J, Ratcliffe J, Salomon JA, Tsuchiya A. Measuring and Valuing Health Benefits for Economic Evaluation. Oxford University Press.
- Drummond MF, Sculpher MJ, Claxton K, Stoddart GL, Torrance GW. Methods for the Economic Evaluation of Health Care Programmes. Oxford University Press.
- Torrance GW. Utility Approach to Measuring Health-Related Quality of Life. Journal of Chronic Diseases. 1987.
- EuroQol Research Foundation. EQ-5D User Guides.
- NICE. Health Technology Evaluation Manual.
Related Concepts (2)
Library
Publications
1
NICE DSU Technical Support Document 8: An Introduction to the Measurement and Valuation of Health for NICE Submissions — Brazier, Rowen, TSD 8 ed., 2011 (NICE Decision Support Unit (University of Sheffield))
An introduction to the measurement and valuation of health for NICE submissions — the QALY, health-state utility values, generic preference-based measures, and the requirements of the NICE reference case.
Frequently Asked Questions (6)
What is a preference weight?
A numerical value reflecting the relative desirability a population or individual assigns to a particular health state or outcome.
Source: Brazier et al. 2007
How does a preference weight differ from a raw questionnaire score?
A raw questionnaire score records how much of a problem a person reports, for instance a higher number for more severe pain, but it says nothing about how bad that problem is thought to be. A preference weight supplies exactly that missing information, expressing on a common scale how desirable or undesirable a state is judged to be. Converting descriptions into weights is what allows different health states to be traded against one another and against survival. Brazier and colleagues (2007) explain this role of preference weighting.
Source: Brazier et al. 2007
How are preference weights derived?
Preference weights are derived by eliciting valuations of health states from a sample of respondents, using methods such as the time trade-off, standard gamble, or discrete choice experiments, and modelling these valuations to assign a weight to every state an instrument can describe. The elicitation reveals how desirable each state is relative to full health and death, and the modelling extends the sample valuations to all possible states. The weights thus embody the preferences of the valuation sample.
Source: Brazier et al. 2007
Whose preferences do the weights represent?
Preference weights may represent the preferences of the general public, imagining the states, or of patients experiencing them, and the two can differ. Many decision-making bodies specify weights from a representative sample of the general public, on the view that publicly funded resources should reflect societal preferences, though using patient values is argued where adaptation makes public valuations too low. The source of the weights is stated, since it affects the utilities and hence the results.
Source: Brazier et al. 2007
How are preference weights used?
Preference weights are used as the utilities that weight time in the calculation of quality-adjusted life years, so that a year in a state with a weight of 0.7 counts as 0.7 quality-adjusted life years. They convert a description of health into a value that can be combined with length of life, providing the outcome measure for cost-utility analysis. The weights therefore directly shape the estimated benefit of interventions.
Source: Brazier et al. 2007
What are the issues with preference weights?
Preference weights depend on the valuation method, which can give different values for the same state, and on whose preferences are elicited, since public and patient values differ. The weights are averages that may not represent every individual, and modelling them to all states introduces assumptions. Because they directly determine quality-adjusted life years and thus cost-effectiveness, these choices carry weight in decisions, which is why the method and source of the weights are scrutinised and reported.
Source: Brazier et al. 2007
Trust Record
Verified by Dr Darrin Baines
British health economist
Professional identity: darrinbaines.org
Verification date: 1 Sep 2025
Content version: 1.0.0
Canonical Identity
- Persistent URI
- https://healtheconomics.wiki/concept/preference-weight
- Term code
- HE-EE-HU-056
Stable URI · Machine-readable · Resolvable · CC BY 4.0