title: Disentangling rectangularization and life span extension with the moving rectangle method.
abstract: OBJECTIVE
  The moving rectangle method is used to disentangle the contributions of rectangularization and life span extension to the increase in life expectancy. It requires the choice of an endpoint of the survival curve that approaches the maximum age at death. We examined the effect of choosing different end points on the outcomes of this method.
  
  
  METHODS
  For five developed countries, survival curves from age 50 years were constructed per calendar year from 1922 onward. Survival values of 0.1, 0.01, and 0.001 were chosen as end points of the survival curve, and the contributions of rectangularization and life span extension to the increase in life expectancy were calculated using the moving rectangle method.
  
  
  RESULTS
  The choice of different survival values as end points profoundly influenced the estimated contributions of rectangularization and life span extension to the increase in life expectancy. When choosing 0.001, rectangularization contributed most years, whereas when choosing 0.1, life span extension contributed most years.
  
  
  CONCLUSIONS
  When the moving rectangle method is used to estimate the contributions of rectangularization and life span extension to the increase in life expectancy, its outcomes depend on the choice of the endpoint of the survival curve.
authors: Leyden Academy on Vitality and Ageing, Leiden, The Netherlands; Section of Gerontology and Geriatrics, Department of Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands.
authors: Frank H
authors: FH
authors: Schalkwijk
authors: Leyden Academy on Vitality and Ageing, Leiden, The Netherlands; Section of Gerontology and Geriatrics, Department of Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: j.j.e.koopman@lumc.nl.
authors: Jacob J E
authors: JJ
authors: Koopman
authors: Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
authors: Eidrees
authors: E
authors: Ghariq
authors: Netherlands Interdisciplinary Demographic Institute (NIDI-KNAW), University of Groningen, The Hague, The Netherlands.
authors: Joop A A
authors: JA
authors: de Beer
authors: Leyden Academy on Vitality and Ageing, Leiden, The Netherlands; Section of Gerontology and Geriatrics, Department of Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands.
authors: David
authors: D
authors: van Bodegom
authors: Section of Gerontology and Geriatrics, Department of Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands; Department of Public Health and Center of Healthy Aging, University of Copenhagen, Copenhagen, Denmark.
authors: Rudi G J
authors: RG
authors: Westendorp
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019049:Developed Countries / Q000706:statistics & numerical data*; D005060:Europe; D005260:Female; D006801:Humans; D008017:Life Expectancy; D008136:Longevity; D008297:Male; D008875:Middle Aged; D016019:Survival Analysis
keywords: Aging; Life expectancy; Life span; Longevity; Moving rectangle method; Rectangularization