Newbie question. I am reading about stationary series and understand that it has many forms:
If I run an augmented dicky fuller test and find that the series is stationary is that sufficient to say that the series is stationary in all respects?
Rejecting the null hypothesis of a unit root after applying the ADF test does not imply that the series is stationary in all respects. The ADF test is devised to detect non-stationarity in the long-term cycle, i.e. the trend of the series. Non-stationarity in other cycles are not inspected by this test. As long as the series exhibits a stationary trend pattern, sources of non-stationarity such as a changing seasonal pattern or a switch in the variance of the series will most likely result in rejecting the null hypothesis of the ADF test.
