The forth chapter: Abnormal value analysisWe discus some kind of abnormal value of time series, that is additive outlier (AO), innovative outlier (IO), permanent level shift (PLS), changing trend (CT).

• 在本章中,我们论述了几种时间序列异常值,即可加的异常值(AO)、新生的异常值(IO)、永久的水平迁移(PLS)、趋势改变(CT)等,并叙述了这几种模型各自相应的建模方法。