If x1<x2<…<xn and the values of lx1, lx2,…, lxn are given, we may wish to estimate the value of the force of mortality at a particular age xi. Two alternative methods of estimation, each used in standard tables, are discussed in some detail.

The most general estimates for each method are given by equations (13) and (22) above, the coefficients {cij} in these equations being defined by equation (11).

In the particular case of consecutive ages, the relevant estimates are given by equations (14) and (23). In this case the values of {cij} for n = 3, 5, 7, and 9 are contained in Tables 1—4 above.