vital index

English

Etymology

From vital +‎ index

Noun

vital index (plural vital indexes)

  1. The ratio of the number of births to the number of deaths in a population over a specific period of time.
    • 1926, Sweeney, James Shirtley, The Natural Increase of Mankind‎[1], page 26:
      Now what is the real biological meaning of the vital index? What does it actually measure? It measures always the present worth of the evolutionary survival value of a population, but implies nothing as to how this present worth is brought about. Furthermore, the vital index implies nothing intrinsic in a population.
    • 1929, Sanders, J., Monograph Series, Issue 1‎[2], page 28:
      The epidemic of influenza in 1918 was almost exclusively responsible for the decline of the vital index to 36.31% below the figure of 1912.

Trivia

It is typically expressed as a percentage using a formula. A vital index greater than 100 indicates that the population is growing (more births than deaths).A vital index less than 100 indicates that the population is in decline (more deaths than births). 

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