As a beginner in this topic I have some basic questions: I would like to know how the CI-bands in e.g. this have plot have to be understood:
What I got so far is that the CI represents which lags are significant, more precisely, those lags with values exceeding the band are significant. So this means, all lags are significant here?
Then I noticed, more out of an accident, that I can kind of redo that by using
acf within the plot command:
Do I have to use
acf always before plotting or is it already done when plotting? It looks totally different, so I wonder about the meaning of the second plot?
Finally, I noticed that I cannot use more than 40 lags. Is that due to the data?