New approach to measuring population aging

The first research results on redefining age and investigating improved methods for predicting life expectancy were published in 2013 by POP researchers.

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Population aging

A new paradigm in conceptualizing population aging has been developed by researchers Warren Sanderson and Sergei Scherbov of the World Population Program (POP). The research was funded by a 2012 European Research Council (ERC) grant of 2.25 million euros awarded to Scherbov. Scherbov and Sanderson, applied the "characteristics approach" to the measurement of population aging.  

Traditional measures, which do not take into account changes in people's characteristics such as improvements in life expectancy and health, are becoming increasingly inappropriate for both scientific and policy analysis. There is now an emerging new paradigm that considers multiple characteristics of people including, but not limited to, their chronological age. 

The initial focus was on four characteristics:

  • chronological age as a quantitative benchmark for measuring the importance of the other characteristics;
  • remaining life expectancy as a forward-looking definition of age;  
  • mortality rate as a rough but easily measurable health indicator;  
  • proportion of adult person-years lived after a particular age for construction of a simple hypothetical demographically indexed public pension system.

Together these four characteristics provide a perspective on an age-old question: how old do you need to be to be considered “old”? This age of transition to "old" varies over time. The authors call the resulting transitions “transition trajectories” – one for each of the four characteristics.

The new approach has strong implications  for research and policy, making it worth reexamining studies on, for example, the effects of dependency ratio on economic growth. The new measure of age can also be used in place of chronological ages in investigations and forecasts of health care expenditures. 


Sanderson WC, Scherbov S (2013). The Characteristics Approach to the Measurement of Population Aging, IIASA Interim Report IR-13-007.


European Research Council (ERC).

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Last edited: 22 May 2014


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