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Exercise

Holt-Winters method with daily data

The Holt-Winters method can also be used for daily type of data, where the seasonal pattern is of length 7, and the appropriate unit of time for h is in days.

Here, you will compare an additive Holt-Winters method and a seasonal naive() method for the hyndsight data, which contains the daily pageviews on the Hyndsight blog for one year starting April 30, 2014. The data are available in your workspace.

Instructions
100 XP
  • Using subset.ts(), set up a training set where the last 4 weeks of the available data in hyndsight have been omitted.
  • Produce forecasts for these last 4 weeks using hw() and additive seasonality applied to the training data. Assign this to fchw.
  • Produce seasonal naive forecasts for the same period. Use the appropriate function, introduced in a previous chapter, and assign this to fcsn.
  • Which is the better of the two forecasts based on RMSE? Use the accuracy() function to determine this.
  • Produce time plots of these forecasts.