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On ratios of random variables and generalised mortality rates

Published online by Cambridge University Press:  14 July 2016

Leigh A. Roberts*
Affiliation:
Victoria University, Wellington
*
Postal address: Institute of Statistics and Operations Research, P.O. Box 600, Victoria University, Wellington, New Zealand.

Abstract

We find the distribution function of a ratio of dependent random variables which can represent a generalised mortality rate in a demographic or life insurance context. Each death in the numerator and each unit of exposure in the denominator are weighted by a random sum at risk, which is assumed to follow a gamma distribution. General results on the existence of moments of ratios of random variables are established, and applied to show that the moments of the rates considered here depend in a simple way on the minimum number of entrants into the mortality investigation.

MSC classification

Type
Research Papers
Copyright
Copyright © Applied Probability Trust 1992 

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References

Feller, W. (1965) An Introduction to Probability Theory and its Applications, Vol. II. Wiley, New York.Google Scholar
Marsaglia, G. (1965) Ratios of normal variables and ratios of sums of uniform variables. J. Amer. Statist. Assoc. 60, 193204.Google Scholar