A study on mortality rates and expectation of life at birth in demography]

An "age-time-area diagram" (referred to as a-t diagram) which is used as the basis for discussing different used and applications of variously defined mortality rates, as well two kinds of measurements for life expectancy is proprosed. The proposal is built upon the Lexis diagram. The a-t diagram is used to define a new way of measuring child mortality, projecting population, and proposing a formula for measuring successive and nonsuccessive life expectancy.