In the above equation, ß measures the rate of increase in mortality with age (a) and ? measures the background mortality. Thus the estimate of senescent mortality by age

for ages above 25.

To consider the effect of specific factors such as prevention of smoking

Decomposition of LE, therefore, provides an opportunity for making more informed projections of life expectancy for the future.

POPULARITY OF STATISTICAL MODELS OVER MATHEMATICAL MODELS

In the recent past, models based on advanced statistical techniques have become more popular than mathematical models ((Jansen, 2007; Vandresse, 2008)). Poisson regression (expressing log of rates as linear combination of independent variables), logit regression (expressing log odds as linear combination of independent variables) and multiple classification analysis are increasingly used by the social scientists. Guo and Harris (2000) used a structural equation model to examine the effect of poverty and other factors on children's intellectual development.