Qi Jin-Peng, Zhang Qing, Zhu Ying, Qi Jie
College of Information Science & Technology, Donghua University, Shanghai, P.R. China; The Australia e-Health Research Centre, CSIRO, Brisbane, QLD, Australia.
The Australia e-Health Research Centre, CSIRO, Brisbane, QLD, Australia.
PLoS One. 2014 Apr 1;9(4):e93365. doi: 10.1371/journal.pone.0093365. eCollection 2014.
Although Kolmogorov-Smirnov (KS) statistic is a widely used method, some weaknesses exist in investigating abrupt Change Point (CP) problems, e.g. it is time-consuming and invalid sometimes. To detect abrupt change from time series fast, a novel method is proposed based on Haar Wavelet (HW) and KS statistic (HWKS). First, the two Binary Search Trees (BSTs), termed TcA and TcD, are constructed by multi-level HW from a diagnosed time series; the framework of HWKS method is implemented by introducing a modified KS statistic and two search rules based on the two BSTs; and then fast CP detection is implemented by two HWKS-based algorithms. Second, the performance of HWKS is evaluated by simulated time series dataset. The simulations show that HWKS is faster, more sensitive and efficient than KS, HW, and T methods. Last, HWKS is applied to analyze the electrocardiogram (ECG) time series, the experiment results show that the proposed method can find abrupt change from ECG segment with maximal data fluctuation more quickly and efficiently, and it is very helpful to inspect and diagnose the different state of health from a patient's ECG signal.
尽管柯尔莫哥洛夫-斯米尔诺夫(KS)统计量是一种广泛使用的方法,但在研究突变点(CP)问题时存在一些弱点,例如它有时耗时且无效。为了快速从时间序列中检测突变,提出了一种基于哈尔小波(HW)和KS统计量的新方法(HWKS)。首先,通过对诊断后的时间序列进行多级哈尔小波变换构建两个二叉搜索树(BST),分别称为TcA和TcD;通过引入改进的KS统计量和基于这两个二叉搜索树的两个搜索规则来实现HWKS方法的框架;然后通过两种基于HWKS的算法实现快速突变点检测。其次,通过模拟时间序列数据集评估HWKS的性能。模拟结果表明,HWKS比KS、HW和T方法更快、更灵敏且更有效。最后,将HWKS应用于分析心电图(ECG)时间序列,实验结果表明,该方法能够更快、更有效地从具有最大数据波动的心电图片段中找到突变点,这对于从患者心电图信号中检查和诊断不同健康状态非常有帮助。