Could some one explain me, what is the confidence band in correlogram and if an autocorrelation coefficient is out of this line, what does it mean?
For example in my Diagramm, lag 14 is significantly high, what does it mean?
Here is the relevan excerpt from the Correlogram wikipedia page:
If the autocorrelation is higher (lower) than this upper (lower) bound, the null hypothesis that there is no autocorrelation at and beyond a given lag is rejected at a significance level of alpha,. This test is an approximate one and assumes that the time-series is Gaussian.
Concerning your example, lag 14 significantly high means, that the data does not reject hypothesis that autocorrelation at 14 lag is not zero. I would suspect seasonality, since lags 7,8, 23, 30 and 39 are significant also.
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