Supplement

To classify RR sequences, we explored linear discriminant analysis (LDA) commonly used for detection of stress (Melillo et al., 2011; Kaur et al., 2014). We used a log-transformation to meet assumptions of homogeneity of variance and normally-distributed residuals. The homogeneity of variances was tested by means of Cochran C statistic. In order to evaluate the overall performance of the classifiers, results of the rest-stress comparisons were quantified by the criteria of sensitivity, specificity, precision, and accuracy. The highest estimates of the total classification accuracy and sensitivity and was achieved by α1 and by recurrent plot measures (Supplement 2).