The following Question comes from Forecasting:Principles and Practice 3rd Edition Chapter 5.11 Exc12:

tourismcontains quarterly visitor nights (in thousands) from 1998 to 2017 for 76 regions of Australia.

1. Extract data from the Gold Coast region usingfilter()and aggregate total overnight trips (sum overPurpose) usingsummarise(). Call this new datasetgc_tourism.
2. Usingslice()orfilter(), create three training sets for this data excluding the last 1, 2 and 3 years. For example,gc_train_1 <- gc_tourism %>% slice(1:(n()-4)).
3. Compute one year of forecasts for each training set using the Seasonal nave (SNAIVE()) method. Call thesegc_fc_1,gc_fc_2andgc_fc_3, respectively.
4. Useaccuracy()to compare the test set forecast accuracy using MAPE. Comment on these.