A stochastic approach to the estimation of the prevalence of IUD: Example of Taiwan, Republic of China

Assuming three patterns of changes in number of new IUD insertions, three stochastic models have been developed for the estimation of the “prevalence” of IUD in situ at a given point of time. The advantages of these models, compared with the conventional ways of estimating IUD prevalence, rest with their ease of use and simplicity of method for calculating variances of the estimates. The models are also useful for family planning administrators to set program targets. A correction factor to estimate the number of IUDs which, although “currently in situ,” are worn by women who have “passed over” the upper age limit of their reproductive spans has also been developed. This is particularly useful in estimating the “effective retention” of IUD.