Table 2.

HRV indices that constitute factors of fABAS, from Hoyer et al (2013b).

HRV index	Calculation	Interpretation
Fluctuation amplitude
Amplitude	20–95 inter-quantile distance (difference between the 20th and 95th percentile of detrended NN interval series)	Fluctuation range of heart beat intervals above an approximated baseline
Complexity
gMSE(3)	Generalized mutual information at coarse graining level 3 of NN series	Complexity of sympatho-vagal modulation
Pattern formation
Skewness	Skewness of NN interval series	Asymmetry, decline of deceleration and formation of acceleration patterns
pNN5	Percentage of differences between adjacent NN intervals > 5 ms	Formation of vagal modulations
VLF/LF	Ratio between VLF (0.02–0.08 Hz) and LF (0.08–0.2 Hz) power	Baseline fluctuation in relation to sympatho-vagal modulations