When forecasting of a seasonal time series is done using stlm() or stlf() in R and no model is specified, what is the default model used? Ps- I read the documentation and searched on the internet but couldn't find any lead.
From the help file:
stlmtakes a time seriesy, applies an STL decomposition, and models the seasonally adjusted data using the model passed asmodelfunctionor specified usingmethod. It returns an object that includes the original STL decomposition and a time series model fitted to the seasonally adjusted data. This object can be passed to the forecast.stlm for forecasting.
If you look at the default arguments, modelfunction=NULL and method="ets". So it uses an ETS model on the seasonally-adjusted data.