I'm trying the classic AirPassengers dataset in R and tried removing the seasonal component using deSeas <- forecast::seasadj(decompose(d,"multiplicative"));
, but it doesn't seem to go away.
Original data:
Seasonality viewed with plot(decompose(d,"multiplicative"))
:
Seasonality adjusted with
deSeas <- forecast::seasadj(decompose(d,"multiplicative"))
plot(deSeas)
But decompose still shows a seasonal pattern, deSeas <- seasadjplot(decompose(ddeSeas,"multiplicative"));
But decompose still shows a seasonal pattern:
I don't understand why there still is a seasonality. Should I de-seasonalize it again? Will arima be able to re-incorporate the single de-seasonalized or double de-seasonalized data back into the predictions that it tries to make?