Sullivan Method
Also known as: Sullivan's Index, Sullivan Health Expectancy Method, Prevalence-Based Health Expectancy, Sullivan Yöntemi
The Sullivan method is a simple, widely used technique for estimating health expectancy — the average number of years a person can expect to live in a given health state, such as free of disability. Introduced by Daniel Sullivan in 1971, it combines an ordinary period life table with the observed age-specific prevalence of the health state, partitioning life-table person-years into healthy and unhealthy years without requiring any longitudinal transition data.
Key highlights
- Extremely economical — requires only a standard life table and one cross-sectional prevalence survey, both routinely available.
- Produces health expectancies that are independent of the underlying age structure, making them directly comparable across populations and over time.
- Conceptually transparent and easy to compute, which has driven its adoption as a global health-monitoring standard.
- Partitions total life expectancy cleanly into healthy and unhealthy years that sum back to the total.
Intuition
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How it works
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When to use it
Use the Sullivan method when you need a robust, comparable estimate of health expectancy — disability-free life expectancy, healthy life expectancy, and similar indicators — from routinely available data: a period life table plus one cross-sectional survey of age-specific prevalence. It is ideal for population monitoring, international comparison, and trend analysis, which is why it underpins global indicators such as healthy life years. It assumes the observed prevalence reflects a stationary process, so the period cross-section stands in for a cohort's experience. It is less appropriate when health states change rapidly over time (the prevalence then lags true transition risk), when reversible transitions and their dynamics are the object of study, or when incidence-based estimates are required; in those cases the multistate (increment-decrement) life table is the more rigorous alternative.
Strengths & limitations
- Extremely economical — requires only a standard life table and one cross-sectional prevalence survey, both routinely available.
- Produces health expectancies that are independent of the underlying age structure, making them directly comparable across populations and over time.
- Conceptually transparent and easy to compute, which has driven its adoption as a global health-monitoring standard.
- Partitions total life expectancy cleanly into healthy and unhealthy years that sum back to the total.
- Prevalence-based rather than incidence-based, so estimates reflect the accumulated history of transitions rather than current conditions and lag real change.
- Cannot capture the dynamics of transitions between health states, including recovery, because it uses no transition data.
- Assumes a stationary process in which the period prevalence cross-section validly represents cohort experience.
- Sensitive to how the health state is defined and measured in the survey, which hampers comparison when definitions differ.
Common pitfalls
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Applications
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Frequently asked
What is the difference between the Sullivan method and a multistate life table?
The Sullivan method weights ordinary life-table person-years by a cross-sectional prevalence of the health state, so it needs only a life table and one survey and is prevalence-based. A multistate life table instead uses observed transition rates between health states and is incidence-based, capturing recovery and the true dynamics of movement. Sullivan is far simpler and more widely applicable but reflects the accumulated past; the multistate approach is more rigorous but demands longitudinal data.
Why does prevalence-based estimation lag true change?
The prevalence of a chronic condition at a given age reflects the cumulative balance of past incidence, recovery, and differential mortality, not just current risk. So when health is changing quickly, the period prevalence cross-section still embeds older experience and the Sullivan estimate adjusts more slowly than the underlying transition rates. During stable periods this is a minor concern, but it matters when interpreting short-term trends.
Do healthy and unhealthy expectancies add up to total life expectancy?
Yes. Because every interval's person-years are split into a healthy share (1 − πₓ)·Lₓ and an unhealthy share πₓ·Lₓ that together equal the full Lₓ, the resulting healthy and unhealthy life expectancies sum exactly to total life expectancy at every age. This clean additive partition is one reason the method is so easy to interpret and communicate.
Sources
- 1.Sullivan, D. F. (1971). A single index of mortality and morbidity. HSMHA Health Reports, 86(4), 347–354.
- 2.Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell.ISBN 9781557864512
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Cite this page
ScholarGate. (2026, June 22). Sullivan Method. ScholarGate. https://scholargate.app/demography/sullivan-method