Some problems in determining the number of acceptors needed in a family planning programme to achieve a specified reduction in the birth rate

Abstract

The paper attempts to revive professional interest in a problem originally considered by Lee and Isbister and which has assumed added importance recently because of the increasing number of national family planning programmes that are being instituted, which require the determination of the number of acceptors needed in a family planning programme in order to achieve a specified reduction in the birth rate. The publication of subsequent papers on births averted by programmes, notably by Potter and Wolfers, each of whom had made some criticisms of the paper by Lee and Isbister, has tended to obscure the differences in the nature between the problem raised by Lee and Isbister, and that discussed by Potter or Wolfers. The paper tries to bring out these differences and points out one of the limitations of the estimates of births averted obtained by using either Potter's or Wolfers's methods, viz. the inability to determine the time period to which the birth reduction refers, thereby further complicating the issues involved in assessing the social and economic implications of births averted by a family planning programme. The paper also points out some of the unrecognized technical considerations which arise in dealing with the `target-setting' problem raised by Lee and Isbister and suggests that stochastic model studies might offer a clue for evolving practical methods for tackling this problem.