APPROXIMATION OF BURST DURATION'S PDFS OF BIRTH-DEATH PROCESSES

Ignas Kazakevičius1, Vygintas Gontis1

1 Institute of Theoretical Physics and Astronomy, Vilnius University, Lithuania

[email protected]

Indicator of long-range memory is considered to be a power-law power spectral density in the low frequency domain [1]. However, many different stochastic processes may have this long-range memory property. In order to identify different stochastic processes and solve previously mentioned problem we are focusing on the analysis of the stochastic processes burst and inter-burst duration's probability density functions (PDF) which can be used to determine whether a particular complex process retains the characteristics of a long-range memory in cases of different inter-burst duration's threshold limits [2].

To generate time series we used the stochastic differential equation (SDE) asymptotically describing agent-based Kirman Birth-Death process. We performed the numerical calculation of burst and inter-burst duration's PDF's dependence on the threshold value of the process. It was shown that such PDFs generated by respective SDE in general case cannot be described by analytical approximation proposed for transformations of Bessel process. However, it was shown that analytical approximation derived in this work can be used to describe the bursts PDF of Bessel process and in specific cases could be used to approximate more complex processes than Bessel process such as agent-based Birth-Death process [3].

Figure 1
Fig. 1. Burst duration's PDFs: a) PDF calculated by solving SDE numerically (crosses), b) analytical PDF approximation [4] (black lines), c) Analytical PDF approximation in a newer work (gray lines) [3].

[1] Beran J., Feng Y., Ghosh S., Kulik R. Long-Memory Processes probabilistic Properties and Statistical Methods, Spinger-Verlag Berlin Heidelberg, 2013, DOI: 10.1007/978-3-642-35512-7.

[2] V. Gontis, A. Kononovičius, Spurious Memory in Non-Equilibrium Stochastic Models of Imitative Behavior, Entropy, 19 (8), 2017, p. 387, 2017, DOI: 10.3390/e19080387.

[3] Kazakevičius I., First Passage Time of Birth-Death processes, Master Thesis, Vilnius University, 2019.

[4] Kononovičius A., Gontis V. Approximation of the First Passage Time Distribution for the Birth-Death Processes, Journal of Statistical Mechanics 2019: 073402 (2019).