时间序列 Time Series

时间序列（Time Series）: Time series (or dynamic series) refers to the series that arranges the values of the same statistical index according to the time sequence of their occurrence. The 

统计指标（statistical indicator）： A complete statistical indicator includes two parts: indicator name and indicator value.

时序点过程（Temporal Point Process）： A temporal point process is a stochastic, or random, process composed of a time- series of binary events that occur in continuous time. They are used to describe data that are localized at a finite set of time points.

时间序列分析（Time Series Analysis）: 

    1. 长期趋势变化（Trend）: The general direction in which the time series is moving. Time series can have a positive or a negative trend, but can also have no trend(when trying to keep stable).

    2. 循环变化（Cycle）: The cycle for time series data refers to its tendency to rise and fall at inconsistent frequencies, e.g. business cycles.

    3. 季节性周期变化（Seasonality）: Time series's tendency to rise and fall at consistent frequencies, e.g. tourism industry. 

    4. 随机性变化（Remainder）: The remainder is what's left of the time series data after removing its trend, cycle and seasonal components.

Additive Decomposition:

Y is the time series data, T is the trend-cycle component, S is the seasonal component, and R is the remainder.

Y = T + S + R