“…In our previous work (Yu et al, 2011), we used the Kullback-Leibler divergence (also called relative entropy) to obtain a symmetrised measure and successfully studied the phylogeny of various DNA sequences based on their probability distributions. The Kullback-Leibler divergence, which is a powerful tool to measure the difference between two probability distributions, has been widely used in many fields, such as bioinformatics (Kaitchenko, 2004; Liu et al, 2014; McClendon et al, 2012; Hoang et al, 2015), genomics (Huang et al, 2014; Lin, 2015; Siegel et al, 2015), and machine learning (Lee and Lee, 2006; Rubinstein and Kroese, 2013). By means of this measure, we performed cluster analysis for those subjects including MDD cases and controls.…”