Different sources indicate different norms for every variability parameter. The most widely-used ranges can be found in the Standards of measurement, physiological interpretation, and clinical use put together by the Task Force of The European Society of Cardiology and The North American Society of Pacing and Electrophysiology. We used averages from several sources in our calculations.

The norms for parameters calculated with your blood pressure numbers are also averages we’ve calculated based on information from different sources.