Time series is essentially data that is recorded in time order. In nearly all cases, the data includes a timestamp with one or more data points being collected at that time. Time series data is commonly seen in fields that analyze trends over time.
Characteristics
- Trends: Drifting up or down
- Seasonality: Regularly occurring
- Cyclic: Exhibits a rise and fall at unknown intervals
- Stationary: Mean & std dev is constant
- Trend-stationary is also possible
Tests
- Engle Granger Method
- Useful for determining if there’s a correlation between two processes
- KPSS test
- Hypothesis test to determine if the process is stationary or trend-stationary