Chart statistics for BBT charts rated and evaluated from January 1 to October 21, 2002:
- Total number of charts: 3,355
- Charts that showed actual (expert-evaluated) ovulation: 3,037
- Charts with anovulation: 318 Charts without calculated OD: 515
- Charts with both actual and calculated ovulation: 2,662
- Charts with calculated ovulation that actually showed ovulation: 2,662/2,840 (94% positive predictive value)
- Charts with ovulation and which were calculated: 2,662/3,037 (88% specificity).
Interpretation: The BabyMed formula correctly calculated the ovulation day within 2 days of the actual ovulation day in 87% of charts, and in 60% of the charts both the calculated and actual days were the same.