Fig 5. Partial autocorrelation analysis of RR-intervals.

For all participants, the partial autocorrelation values are large at the first few lags and then become smaller. For many participants, the dependence of the current RR-interval on a lag of beyond eight is small. Consequently, we chose to investigate model orders q = 1, 2, …, 8 for each participant and selected the value of q giving rise to the smallest KS distance.