The distribution of events in the human menstrual cycle.

Daily reports of 85 married couples concerning their sexual behaviour for about 3 menstrual cycles per couple were organized according to menstrual events by using six techniques of aggregation. While there were some similarities among the different displays, including an apparent peak about 6 days before mid-cycle, different methods of aggregation produce widely different frequency curves. It is concluded that there is no single method of display of events of the menstrual cycle which will fit all investigations.