Menstrual synchrony
Strassmann argued menstrual synchrony defined as menstruation overlap should be quite common. For example, the expected difference by chance between two women with 28-day cycles—which is approximately the average length of menstrual cycles of women at the age —is 7 days. Considering that the mean duration of menses is 5 days and the range is 2 to 7 days, the probability of menstruation overlap by chance should be high.
Chandravakyas
The Moon's orbit approximates an ellipse rather than a circle. The orientation and the shape of this orbit is not fixed. In particular, the positions of the extreme points,
the point of closest approach (perigee) and the point of farthest excursion (apogee), make a full circle in about nine years. It takes the Moon longer to return to the same position, perigee or apogee, because it moved ahead during one revolution. This longer period is called the anomalistic month, and has an average length of 27.554551 days (27 d 13 h 18 min 33.2 s). The apparent diameter of the Moon varies with this period. 9 anomalistic months constitute a period of approximately 248 days. The differences in the longitudes of the Moon on the successive days of a 248-day cycle constitute the "Chandravākyas". Each set of "Chandravākyas" contains a list of 248 "Vākyās" or sentences.