Sex-specific trends in mortality for the aging population in Norway: a model with age, period, and cohort effects.

During the last few decades, the citizens of most western countries have experienced an increased expectation of life. The rate of this change differs for males and females. We evaluated reasons for this pattern, using a Poisson model, with age, period, and cohort effects applied to vital statistics data from the Central Bureau of Statistics of Norway. The data comprised the total Norwegian population aged 45 to 104 years who died in the period from 1966 until 1986. Differential changes in life expectancy for the elderly are explained by differences in sex-specific cohort effects. We also observed an extra-Poisson variation, or overdispersion, in the distribution for females.