Figure 10.

Statistical significance of the nonlinearity test on scale coefficients of heart rate. Each point represents the two-sided, type-I error probability to reject the null hypothesis comparing scale coefficients of the original series and of Fourier-phase shuffled surrogate series at each scale τ and at each moment-order q; differences significant at p < 0.01 are indicated in yellow. The temporal scale τ, in seconds, is obtained multiplying the box size, n, by the mean R-R interval (see Figure 8).