Are there pragmatic bounds on how far ahead one can use an ARIMA or Exponential Smoothing forecast? I have 2 years of weekly data, yet the problem I am trying to solve requires a forecast that is 12 months out.
I'm thinking that a simple average of the LY and LLY data:
TS(week 44 year 3) = [TS(week 44 year 2) + TS(week 44 year 1)]/2
would be just a good a guess as whatever ARIMA or ETS would give me.
Is this indeed a more pragmatic approach than a more involved forecasting method?
Some of the data show a potential year to year trend, but are two years enough to decide that the TS is trending in a given direction ?