Measures of autocorrelation describe the relationship among values of the same data series at different time periods.
The number of autocorrelations calculated is equal to the effective length of the time series divided by 2, where the effective length of a time series is the number of data points in the series without the pre-data gaps. The number of autocorrelations calculated ranges between a minimum of 2 and a maximum of 400.
Autocorrelation formula:
where rk is the autocorrelation for lag k.
Related statistics: