How to address a vary basic question: which tools at hand to check if a series candidate for SA

[andreranza]

Maybe an idea for an exercise to consolidate a fundamental question that might still be forgotten. I realized it on myself when I started to call seas() like a monkey without even asking myself whether it made sense what I was trying to do. I don't know where this would fit best. This, for sure, is part of the "getting started" section. Before starting with seas(), which tools can I use to explore a series, especially in case where the seasonal pattern is not so evident with eye-balling? It would be nice to have a dedicated small section listing all the tools needed to squeeze a series before starting modeling:

• plot(ts)
• plot(decompose(ts))
• plot(stl(ts, s.window = "periodic"))
• monthplot(ts)
• acf(ts)
• qs(seas(ts))

[andreranza]

This is already addressed in "presence of seasonality" chp.

[andreranza]

I wonder if this chp should be moved as a level 0 chp and make a ref to the data issue section of the book.