DEVELOPMENT OF NEW FORMULAS TO IDENTIFY THE FERTILE TIME OF THE MENSTRUAL-CYCLE

The calendar method is perceived to be less effective than other metho ds of family planning. A large existing data set was used to determine how well the fertile time is identified using the traditional calenda r method formula and to determine if better formulas could be develope d to identify the fertile time more accurately and require less abstin ence. We compared the traditional formula with three alternatives, two of which were developed for this analysis. All three alternative form ulas performed better than the traditional formula in identifying the presumed fertile time. The result of our analysis is a summary table w hich can be used to select the best rules for testing the effectivenes s of the calendar method. (C) 1996 Elsevier Science Inc.