Construction of Mortality Table

Construction of Mortality Table

In the construction of a mortality table, the investigations which are undertaken are designed to yield at each age, x, the rate of mortality , that is, the probability that a life age x will die within a year. The two principle sources of life tables are general population statistics obtained from census and the mortality records of life insurance companies.

An initial age is chosen and a convenient number of lives is assumed to exist at that precise age. This number, called the radix, is usually a round number such as 1,000,000 or 10,000,000. The mortality rate is applied to this number of lives to get the number that will die at this age. Hence the number of lives (survivors) at the next age is obtained by reducing the radix by this number of deaths.

The number of survivors of the original group (radix) who have now attained age x is designated by . The number of persons in the group who die after attaining age x but before reaching age x+1, is represented by .

Thus :

Lx+1 = Lx-dx where dx = Lxqx

The 1980 Commissioner’s Standard Ordinary Mortality Table (1980 CSO Table)

Male				Female
Age	Number living	Number dying	Mortality rate per 1000	Number living	Number dying	Mortality rate per 1000	Age
0	1,000,0000	41 800	4.18	1,000,0000	28 900	2.89	0
1	9,958,200	10 655	1.07	9,971,100	8 675	.87	1
2	9,947,545	9 848	.99	9,962,425	8 070	.81	2
3	9,937,697	9 739	.98	9,954,355	7 864	.79	3
.	.	.	.	.	.	.	.
25	9,663,007	17 104	1.77	9,767,317	11 330	1.16	25
26	9,645,903	16 687	1.73	9,755,987	11 610	1.19	26
.	.	.	.	.	.	.	.

The symbol means the probability that (x) will live to reach age x + n. Out of the persons alive at age x there are survivors at age x + n. Thus

npx = Lx+n / Lx