Multivariable flexible modelling for estimating complete, smoothed life tables for sub-national populations

Research output: Contribution to journalArticle


BACKGROUND: The methods currently available to estimate age- and sex-specific mortality rates for sub-populations are subject to a number of important limitations. We propose two alternative multivariable approaches: a relational model and a Poisson model both using restricted cubic splines.

METHODS: We evaluated a flexible Poisson and flexible relational model against the Elandt-Johnson approach in a simulation study using 100 random samples of population and death counts, with different sampling proportions and data arrangements. Estimated rates were compared to the original mortality rates using goodness-of-fit measures and life expectancy. We further investigated an approach for determining optimal knot locations in the Poisson model.

RESULTS: The flexible Poisson model outperformed the flexible relational and Elandt-Johnson methods with the smallest sample of data (1%). With the largest sample of data (20%), the flexible Poisson and flexible relational models performed comparably, though the flexible Poisson model displayed a slight advantage. Both approaches tended to underestimate infant mortality and thereby overestimate life expectancy at birth. The flexible Poisson model performed much better at young ages when knots were fixed a priori. For ages 30 and above, results were similar to the model with no fixed knots.

CONCLUSIONS: The flexible Poisson model is recommended because it derives robust and unbiased estimates for sub-populations without making strong assumptions about age-specific mortality profiles. Fixing knots a priori in the final model greatly improves fit at the young ages.


  • Bernard Rachet
  • Camille Maringe
  • Laura M Woods
  • Libby Ellis
  • Devon Spika
  • Claudia Allemani
External organisations
  • London School of Hygiene and Tropical Medicine
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Public Health, Global Health, Social Medicine and Epidemiology


  • Adolescent, Adult, Aged, Aged, 80 and over, Child, Child, Preschool, England/epidemiology, Female, Humans, Infant, Infant, Newborn, Life Expectancy, Life Tables, Male, Middle Aged, Models, Statistical, Multivariate Analysis, Poisson Distribution, Young Adult
Original languageEnglish
Number of pages9
JournalBMC Public Health
Publication statusPublished - 2015 Dec 16
Publication categoryResearch
Externally publishedYes