How can a time-series data be declared as stationery?

How can a time-series data be declared as stationery?

Checks for Stationarity in time-series data

  1. Look at Plots : plot a run sequence plot to see anything with an obvious trend or seasonal effects
  2. Summary Statistics : partition your data into intervals and check for obvious or significant differences in summary statistics
  3. Statistical Test : use statistical tests if the expectations of stationarity are met or violated.
    ref:https://medium.com/@kangeugine/time-series-check-stationarity-1bee9085da05
    ref:https://towardsdatascience.com/detecting-stationarity-in-time-series-data-d29e0a21e638