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  3. ARIMA Models in Python

Exercise

Seasonal ACF and PACF

Below is a time series showing the estimated number of water consumers in London. By eye you can't see any obvious seasonal pattern, however your eyes aren't the best tools you have.

In this exercise you will use the ACF and PACF to test this data for seasonality. You can see from the plot above that the time series isn't stationary, so you should probably detrend it. You will detrend it by subtracting the moving average. Remember that you could use a window size of any value bigger than the likely period.

The plot_acf() function has been imported and the time series has been loaded in as water.

Instructions 1/3

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  • Plot the ACF of the 'water_consumers' column of the time series up to 25 lags.