2) Using the Gretl GUI, can I perform a classical decomposition similar to
that performed by Minitab (e.g., see Chapter 7 of Minitab 13 manual)?

3) If I can't do it with the GUI, can you offer some guidance on how to use
the command line to do this?

Thanks for the help.

Tom

Just select your serie then go to: Variable>ARIMA-X-12, that'll give you the option to save the serie's components... it uses an "hybrid" decomposition, using additive and multiplicative terms at the same time, but it's supposed to be better than the clasical decomposition.

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Marcos Larios Santa Rosa