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. 2021 Sep 1;18(17):9229. doi: 10.3390/ijerph18179229

Figure 3.

Figure 3

Methods used for the feature extraction process. (A) Poincaré plot, (B) Sample entropy, and (C) Detrended fluctuation analysis. All three approaches evaluate the level of variability in time-series data. For numerical values, the Poincaré plot method was used; for waveform data, sample entropy and detrended fluctuation analysis methods were used.