CONFIDENCE-INTERVALS AND SAMPLE-SIZE CALCULATIONS FOR THE SISTERHOOD METHOD OF ESTIMATING MATERNAL MORTALITY

The sisterhood method is an indirect method of estimating maternal mor tality that has, in comparison with conventional direct methods, the d ual advantages of ease of use in the field and smaller sample-size req uirements. This report describes how to calculate a standard error to quantify the sampling variability for this method. This standard error can be used to construct confidence intervals and statistical tests a nd to plan the size of a sample survey that employs the sisterhood met hod. Statistical assumptions are discussed, particularly in relation t o the effective sample size and to effects of extrabinomial variation. fn a worked example of data from urban Pakistan, a maternal mortality ratio of 153 (95 percent confidence interval between 96 and 212) deat hs per 100,000 live births is estimated.