Unbiased entropy estimates in stress: A parameter study

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• 作者：Aleksandar Boskovic  ; [Author Vitae] ; Tatjana Loncar-Turukalo  ; [Author Vitae] ; Olivera Sarenac  ; [Author Vitae] ; Nina Japundzic-Zigon  ; [Author Vitae] ; Dragana Bajic ; ^{dragana.bajic@gmail.com}  ; [Author Vitae]
• 关键词：Approximate entropy ; Sample entropy ; Pulse interval ; Stationary random processes ; Threshold ; Embedded dimension ; Stress
• 刊名：Computers in Biology and Medicine
• 出版年：2012
• 出版时间：June, 2012
• 年：2012
• 卷：42
• 期：6
• 页码：667-679
• 全文大小：1934 K

文摘

This study proposes a method for obtaining a stable working point that enables the unbiased estimates of the approximate entropy and the sample entropy. Pattern length, normalized threshold, time delay and tines series length are levels of freedom that are considered. Pulse interval signals used for the experiment are recorded from laboratory animals with different likelihood of developing cardiovascular disease - normal and borderline hypertensive rats - exposed to the acute and to the chronic stress. It is shown that the threshold level is the major source of the instability, and that the generally accepted and widely used methods for a threshold choice may lead to an incorrect psychological interpretation. A method for the threshold level correction is proposed.