thetaf(y, h=ifelse(frequency(y)>1, 2*frequency(y), 10), level=c(80,95), fan=FALSE, x=y)
summaryis used to obtain and print a summary of the results, while the function
plotproduces a plot of the forecasts and prediction intervals.The generic accessor functions
residualsextract useful features of the value returned by
rwf.An object of class
"forecast"is a list containing at least the following elements: is a list containing at least the following elements:
The series is tested for seasonality using the test outlined in A&N. If deemed seasonal, the series is seasonally adjusted using a classical multiplicative decomposition before applying the theta method. The resulting forecasts are then reseasonalized.
Prediction intervals are computed using the underlying state space model.
More general theta methods are available in the
Hyndman, R.J., and Billah, B. (2003) Unmasking the Theta method. International J. Forecasting, 19, 287-290.