Session Ready
Exercise

Autocorrelation of seasonal and cyclic time series

When data are either seasonal or cyclic, the ACF will peak around the seasonal lags or at the average cycle length.

You will investigate this phenomenon by plotting the annual sunspot series (which follows the solar cycle of approximately 10-11 years) in sunspot.year and the daily traffic to the Hyndsight blog (which follows a 7-day weekly pattern) in hyndsight. Both objects have been loaded into your workspace.

Instructions
100 XP
  • Produce a time plot and ACF plot of sunspot.year.
  • By observing the ACF plot, at which lag value (x) can you find the maximum autocorrelation (y)? Set this equal to maxlag_sunspot.
  • Produce a time plot and ACF plot of hyndsight.
  • By observing the ACF plot, at which lag value (x) can you find the maximum autocorrelation (y)? Set this equal to maxlag_hyndsight.
    Loading