A comparison of methods to interpret the basal body temperature graph.

Specific criteria are given for several methods of determining the basal body temperature shift. The specific criteria selected have been coded for a uniform interpretation by computer, and interpretations have been compared for 8496 charts. Our results indicate that the method that defines the temperature shift as 0.3 degrees F or more above the running low average for at least 3 consecutive days provides the best concurrent chart interpretation method. A method that creates a smoothed curve that transects the average of all temperatures on a completed graph provides a good retrospective method for identifying the temperature shift. Both the temperature averaging technique and curve smoothing technique identified a temperature shift in more than 95% of the charts with complete temperature readings.