Statistics and graphs for heart rate variability: pNN50 or pNN20?
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Updated: Aug 31, 2026

Impedance Pneumography for Minimally Invasive Measurement of Heart Rate in Late Stage Invertebrates
Published on: April 4, 2020
1Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia. phutchin@psy.mq.edu.au
Abstract:
Two measures of heart rate variability, pNN50 and pNN20, are compared. A non-linear transformation of these measures is proposed, that is helpful in understanding their interrelationship. Provided a valid statistical test is employed, results from analysing pNN20 are likely to be equivalent to those from analysing pNN50. Arguments recently made by Mietus et al (2002 Heart 88 378-80) against the commonly used pNN50 are unconvincing.
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